When a "straight" man has anal sex with a gay man under the pretense that it is his first time. (see Jim the Nickel) However, is very experienced in the act.
Harold went home with that guy last night becaue he thought he was getting to Jim the Nickel but found out he ended up with Phil the Half Dollar.
A task so prolonged or difficult, it seems as though you're taking on more than you bargained for. Once completed, you feel so irritated (or relieved, depending on the situation) that you can't help but talk about it to someone.
Sophie: I didn't get picked up yesterday afternoon and had to walk home. It took me two bloody hours!
John Smith: That must've been a mission and a half.
When you are fingering a girl, but unsure of how many fingers to use, you decide that 4 fingers is the best option. The orientation of your 4 fingers should be vertical, in the same plane as the vagina.
Daaaaaamn! You sawed a bitch in half?!?! She must belooseAF!
When you’ve still got half a pint left but your mate offers you a drink and you don’t want to miss out, so you get a half pint with which to top up the glass. A common scenario since the decline of the fishing industry, so fishermen sit at a ‘spoons nursing a pint instead of fishing.
Ray: Want a pint mate?
Hank: Still got half, I’ll take a fisherman’s half