Back in 2nd grade we used to have these cards. You'd have to pull a card everytime you had to use the bathroom, and when you ran out, you couldn't use the bathroom. I always thought I'd get a reward for never going, so instead, I just peed myself in class all the time.
No one found out ;D
And I remember one time I farted and I blamed it on my shoes rubbing together and making the noise.