What is a cool prank to pull on a teacher in Halloween?

This is what I'm gonna do for a late April Fools: If your teacher CAN'T STAND snakes, get a fake one (you can easily buy them at Walmart in the toy section) and hide it near, in, or under his/her desk. Warning: This is NOT a prank for a teacher with a bad sense of humor. The following is also not a good idea for those teachers. This is pretty lame, but it can be for your classmates too. Get a bag of Oreos and scrape the frosting out of the middle. Refill the middle with toothpaste and make the packaging look new. Also, if your teacher is a HUGE fan of chocolate, tie a string to his/her favorite chocolate and when he/she is about to grab it, yank the string. That's all I have. Good luck. ;-)