Someone doing something that they shouldn't be doing e.g. a ref giving a bad decision at a game, a child playing with a box of matches, a garda pulling up someone for pissing in a dark alley etc.
Used as an exclamation at something happening. Eg. at a hurling match when a person scores a goal in a humurous way a person can joke.
"Did ya see that, Up she flew and the cock flattened her!"