When a girl goes down on a guy and he ejaculates in her eye, causing a severe burning sensation, and a subsequent winking of one eye -- much like a Colonel's Monocle.
As I walked out of my room at 3:00 am to take a wiz, I noticed my roommate’s girlfriend standing at the sink, flushing her eye out. I asked, "Colonel Mustard?" And she replied, in a saddened a whimper, "mmmhmmmm."
A dirty practical joke, where a squeeze mustard bottle is shoved into the victim's ass nozzle first and squeezed, ejecting the mustard into said victim's ass. Originated by the infamous John Gagain, coffee potter extraordinaire.
1. When Billy passed out naked after a night of drinking, his friends gave him a Colonel Mustard. Boy was he surprised!