Nomen agentis.
A person whom no prior social contact have been made whit. But the estimate is that the odds are even 1:1 to engage in sexual contact whit this person that same night.
Usually a person of lower to even socioeconomic status than the person using the expression.
"See that girl over there? She's coinflip."
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Friend: "I heard that you got lucky yesterday?"
A booty call with an amount of uncertainty to it. In other words, if you make arrangements expecting sex with the other person, but are not entriely sure the sex is going to happen.
A term usually used by olderfolk to explain what kids are doing when they are actually smoking marijuana
While crouched over the busIsle in the back, passing a blunt, you and your friends hear the driver yell, "What are you kids doing back there!? Flipping Coins!?