Party Picasso
The Party Picasso is a popular prank that is common at parties, especially ones where lots of people are drunk/asleep. The prankster defecates into the palm of their hand, walks over to someone who is asleep/unconscious and uses the "brown paint" to paint on the victim's forehead. Paintings can range from the classic schlong to a funny word/phrase. For bonus points, the prankster can shove the leftover "paint" into the victim's mouth for a surprise.
Jerry: Never fall asleep at the party.
Jessica: Why not?
Jerry: Last time I did, Larry pulled a Party Picasso on me.
Jessica: Why not?
Jerry: Last time I did, Larry pulled a Party Picasso on me.