I think I made this up since no one taught me, allthough someone allready knew this.
Suppose you have a wrinkled shirt, but want to use it, but don't want to wash it just to use it. All you do, is wet your hands, put your shirt against your chest, and, in a sliding motion down, press down your wet hands, and get rid of the wrinkles. Something like if you were feeling your own chest and abs, but in a pressing motion, like getting bubbles out of that sticky plastic things.
Turn the shirt over, and repeat process with the other side of the garment, and you're done!