Messed Up, Fucked Up. Somethin u did or a place.

To have messed up, to have made a mistake

To ejaculate on a girls face

when a woman's vagina and rectum fuse,then ulcerate, causing feces to come out of the vagina.

After a good doggie style romp, the jizz left on the tip of your cock gets rubbed into the chicks bunghole. A little poop gets mixed in during the rubbing and you muck it up.

Muckit is when you take your cock and push it around in your bitches asshole...you smoosh around her shit and your gizz.

The time period when Valve released a TF2 update with spaghetti code that forced the crate series to always drop unusuals. This resulted in the unusual market crashing with absolutely no survivors left.