When I need a mental health day, I usually call in with a severe migraine that is not responding to meds. I actually do suffer from migraines, so this has an air of truth, plus there are no lingering symptoms that co-workers could look for the next day. Please note that I do not do this often! Luckily I also work somewhere that will let me work from home on those days I really need a break.

I think the truth is actually the best: I need a mental health day. I know you said that some managers don't understand this, and you're right. But I still wouldn't lie about being sick or make up an excuse. I would simply tell my manager that I'm stressed and that stress is a physical condition that wears on the body and the mind, and that I will be a better employee and do a better job if I have a day to take a break, and that I have the sick leave to accommodate that.

When I worked in victim advocacy, we were allowed one 'no questions asked' mental health day off per month with pay, because they understood that a high-stress job like that would require it to keep turnover low. It was a good agency I worked for in that respect. I'm not sure I'd work for a company that couldn't understand the need for mental health breaks now and again as long as it's not habitual and affecting the job negatively.

That said, there were times in the past before I became self employed that I used to lie in bed and wonder if I could call in dead to work.

It would be great for workers if more employers had "no questions asked" days for things like this. Being self employed, I've never really had a chance to polish up on my sick day excuse skills. I would likely just call in and try to explain, though that would likely not win me any points.

Stomach flu.
If you can actually work the words, "explosive diarreha" into your delivery without laughing, you're gold.

In all seriousness, the stomach flu works every time. NO-one wants THAT! Just say you've been up since 4 a.m. throwing up from both ends and sound exhausted and you'll have a couple of days to yourself!

Note*: should you actually be using said excuse for outdoor activity (like golf or something), bring sunscreen. It's hard to explain a sunburn when you've been "in the bathroom" for a couple of days!!

You can use any excuse if you do the calling FIRST thing in the morning before you speak **at all** to anyone. Simply wake up and call. when you talk to the boss deliver the message (insert clever sickness excuse) with the first spoken breaths of the day. all gravely and hoarse whatever you say will be taken seriously as the voice that comes out of your mouth will sound as sick as you need to be to downright deserve a day off.

If you can, I would just say something like "I am not feeling able to come into work today. I think it's best for me, as well as the productivity of the office, that I stay home today." That's the truth, without getting specific. If you need to lie, I would tell him your back is out. No need to try to sound sick. Just a very simple "I need to lay down today, lest I make it worse and miss more work" should suffice.

Poor guys. Women can always get away with calling in sick without being asked for details. Believe me, "feminine problems" never prompts someone to ask for more information :)

Are we talking actually sick? If so here's some great tips from lifehacker:
http://lifehacker.com/116185/how-to-call-in-sick

And if you're just needing a day to yourself, dont shove tissue in your mouth and talk with a raspy voice... try these:
http://www.wikihow.com/Call-in-Sick-when-You-Just-Need-a-Day-Off

Excuses I have used.

My mother in law laid her Harley down at Bike Week. (What? Coulda happened..)
My stigmata is acting up. (Yay working for Hindu people)
I just bought a used car for 2 grand over value. I'm calling in stupid. (My job was accounts auditing)
I fired you yesterday, if you want to keep your job, you will work for me. (Boss was out of town)

But the best, works every time excuse I have..

Vague description of flu-like symptoms. Nobody goes to the Doc to get diagnosed before calling in. Try to do it the night before, around 3am, so the voicemail of your call is timestamped. Don't be drunk. If you are married, have your wife call the office in the morning to confirm that you are unable to work. Just to let them know and all that. You don't want to say it IS the flu, or commit to anything. When you show up to work the next day, folks expect you to look a certain way after the flu. Or at least be sniffling or congested. When you show up fine, you want to be able to say "Must've just been the Taco Bell" or something to that effect.

General flu-like symptoms work well because nobody wants it to spread, they don't want to be sick, or be contagious and make their kids sick. It's common enough to be believable. And honestly, it could have been anything from indigestion to food poisoning.

food poisoning. works for me =)

I work in a nursing home so I try not call in sick. But one day I was really freaking out over stress. I went to work anyway and they ended up sending me home early b/c I was having a spazz attack.

But, if you really want to try it, get a big bowl of water and gummy bears. Call in and say you're feeling really sick and feel like you could pu... then dump the water and gummy bears into a sink of water. It sounds like puke.

BIG IMPORTANT THING HERE: if you are living in a small town, stay home... or look sick in the grocery store and head straight to the meds sections. You'll blow it if anyone sees you out acting just fine.

If you a woman and have a male boss, you can always use a "girl" problem as an excuse. As soon as you say "cramps", he'll hang up the phone with a shudder and you'll be off the hook.

The excuse that always worked best for me with no questions asked is "some kind of stomach bug". You don't have to go into detail, because everybody knows what a stomach bug involves. When you show up the next day, just say "I'm still not 100%, but I"m much better. Must've been a 24 hour thing."

If you've actually ever had a 24 hour stomach bug, you know it's a serious illness. The best thing about it is that everyone has had one, so it's not something you have to explain, or that they expect you to go get a doctor's excuse for.

That being said, I usually go to work, even sick, and make them send me home. The only time I stay home sick from work is if I literally cannot get out of bed.

When I worked for a major discount retailer, I asked the manager of our department to send one girl home who obviously had the flu, and was probably infecting everyone else. She didn't want to ask to go home because she had been out too much, and was afraid she would get fired.

Tell them you think you have food poisoning from something you ate, and that you have been throwing up all night long. You pulled your back out working on your house. If you need more than one day off of work tell them you think you have the swine flu bet that would work.

It depends on the manager and the company, one answer does not work with everyone.

If the company's personnel book says you allowed to take sick days, but it does not say you must provide a reason or proof, then I would simply say that I am sick and not provide any explanation.

Your manager will think less of you if he thinks you are lying to him about the reason you are sick.

NB. I have not experienced any companies in the last 5 to 10 years which still had sick days. They provided personal days off and no reason was required to take a personal day off.

The appropriate answer really depends on your situation. With some employers, you can simply say “I need to call-in sick today”, with no questions asked. If this is the standard in your workplace, count yourself lucky. Most bosses will request, or at least expect, some sort of excuse.

Remember that your excuse has to be believable. Try to come up with something common enough that it won't require any explanation. The last thing you want is to be making up symptoms of some exotic illness you don’t actually have. Pretending to have been suddenly stricken by malaria, leprosy, or flesh-eating bacteria will not get you a day off, and may get you fired. Claiming something like Swine Flu or food poisoning would a little better, but only once, and only for a limited period of time. Be aware that naming a specific illness may prompt your boss to ask for documentation from your Doctor. You’re more likely to be successful with something common like migraines, cough/cold, pulled muscles, etc.

When you call in, try to keep it short. Resist the urge to ramble on about all your symptoms, how and where you got sick, etc. The more you talk, the easier it is to trip yourself up with bad information. Just keep it short. It may help you to write it out and read it over the phone. Try something like “Hello Boss. I’ve come down with a bad cold and I won’t be in tomorrow. Thanks.” If you don’t think you can stand up to questioning, leave a voicemail early in the morning or late the night before.

Tell your boss that your "give a damn" is broken for at least the next 24 hours so you won't be able to make it in to work today.

Family Emergencies are the best excuse. They provide a valid excuse that is tacky to pry into. If you use it a lot it becomes suspicious but used sporadically it creates an easy "no way to find out I'm lying" excuse.

Tell the truth, by making it the truth... get rip-roarin' drunk the night before, such that you're going to have a hangover.

Leave the alarm clock set so that you wake up at normal time, then immediately call the boss and tell him you're sick, and he will be able to tell by the sound of your voice that you're telling the truth.

The catch is... you'll have to actually do what people do when they're sick... which is stay at home and get better, but locking the door and drawing the drapes and taking the phone off the hook is what you were going to do for your "personal mental health" day anyway... right?

Besides... half the time... getting ripped on rum or brandy or tequila *is* what was required for personal mental health, so taking the next day off to recover can still be seen as a legitimate aspect of an over-all day for personal mental health.

Just don't make a habit out of it, and work hard enough when you go back for you to have done as much over the *week* as you would do normally.