'Fess up -- have you ever called in sick when you're feeling fine? If so, you're in good company.

A new survey by CareerBuilder.com finds 32 percent of workers have done just that in the last year. Senior career adviser Jennifer Sullivan said many people are using sick days as "mental health days" to catch up on sleep or simply relax.

One in 10 admitted to doing so three times or more in the last year.

According to Sullivan, many employers are honoring that. But she warned that using sick days as vacation days can get you in trouble, especially if a colleague spots you.

And while some employers said they typically don't question excuses given, others were more skeptical. Twenty-seven percent of hiring managers reported they have fired a worker for calling in sick without a legitimate reason.

And for those who told the teacher, "My dog ate my homework," it turns out there are grown-up versions. Employers have heard plenty of unusual excuses for not coming to work, including one guy claiming his mother-in-law poisoned him, or the fellow who said he broke his leg snowboarding off the roof while drunk.

The most popular motivator for missing work was the need to relax, according to nearly half (48 percent) of workers. Twenty-four percent of workers pointed to the desire to catch up on sleep while 20 percent cited personal errands. Other top reasons included doctors appointments (17 percent), plans with family and friends (16 percent) and housework (16 percent).

"Although an improvement from last year, the amount of unexcused absences from the office is significant and can be indicative of employee dissatisfaction," said Rosemary Haefner, Vice President of Human Resources at CareerBuilder.com. "Forty-five percent of hiring managers have caught an employee calling in sick with a fake excuse. This begs two questions: do you have the right employees working for your organization and do you have the right employee management practices in place for your staff?"

One in four workers said they consider their sick days to be equivalent to vacation days and treat them as such.

Comparing genders, women were more likely to take a sick day when they were feeling fine. Thirty-seven percent of women called in sick with bogus explanations compared to 26 percent of men, the survey said. On the employer side, men were more likely to terminate an employee for an unexcused sick day, CareerBuilder reported. Thirty-five percent of men said they have fired an employee for calling in sick with a fake excuse compared to 15 percent of women.

Workers who are chronic offenders may be running out of ideas. Forty-one percent of hiring managers said they have received unusual or suspicious sick day alibis. Sixty-two percent did not believe them, according to the survey. When asked to share the most unusual excuses employees gave for missing work, hiring managers offered the following examples:

1) Employee was poisoned by his mother-in-law.
2) A buffalo escaped from the game reserve and kept charging the employee every time she tried to go to her car from her house.
3) Employee was feeling all the symptoms of his expecting wife.
4) Employee called from his cell phone, said he was accidentally locked in a restroom stall and no one was around to let him out.
5) Employee broke his leg snowboarding off his roof while drunk.
6) Employee's wife said he couldn't come into work because he had a lot of chores to do around the house.
7) One of the walls in the employee's home fell off the night before.
8) Employee's mother was in jail.
9) A skunk got into the employee's house and sprayed all of his uniforms.
10) Employee had bad hiccups.
11) Employee blew his nose so hard, his back went out.
12) Employee's horses got loose and were running down the highway.
13) Employee was hit by a bus while walking.
14) Employee's dog swallowed her bus pass.
15) Employee was sad.

The survey was completed in September 2006 and included 1,650 workers and 1,150 hiring managers nationwide.