It's when your friend is sleeping, and you take his thumb and shove it up his ass. then you take the shit covered finger and rub it right under his nose. it looks like they have the Adolf Hitler mustache, aka the square above the lip.
John: You smell that shit?
Tom: LOL no...i don't ;)
John: something smells like shit around here.l funny.
Tom: XP!!!! Someone gave you the Hitler!!! LOL LOL OMFG!!1!!
John: Shit. that's fucked up