This is an easy mac terminal prank to make your friends desktop clean. They'll freak out wondering where everything went. Then you look at it, think for a while and say you can fix it. Maybe have them get you a coke first. then you just type in another command and its back to normal!
Step 1: Hiding
open terminal and type:
chflags hidden ~/Desktop/*
then hit enter and the icons will dissapear!
Step 2: Showing
After they have gotten you a coke, open terminal again and type:
chflags nohidden ~/Desktop/*
this will show the icons again=)