Put tape over the optical sensor of someone's mouse.

 868

1  

Hide an alarm clock in someone's bedroom and set it for 3:00 a.m.

 805

0  

Take a squirt gun into the rest room stall next to someone and shoot little drops over the wall every couple of seconds while pretending to pee.

 777

0  

Paint a bar of soap completely with clear nail polish so it won't suds up.

 760

1  

Fill someone's hair-dryer with baby powder.

 763

1