Replying to Turtling back packs

does anyone have this problem in their school. For those of you who don't understand what that means. It's when you;
 steal someones backpack,
 take everything out,
 turn it inside out
 then put the stuff back in and zip it up
once it's done and zipped up slide it back to them and then hopefully they don't notice untill the end of class and they have to carry it around untill they get to there next class and un-turtle it

Last tuesday there was an epidemic and my Dakine Helipack pro got turltled. since today is april fools day, everyone was turlting back packs again. Pretty funny