prop bet
n.— «If placing a bet on either team or the over/under is just not enough to satiate your gambling jones, there are numerous other ways to find action—these wagers are called “prop bets.” Do you have enough confidence in the Cardinals to wager on them without taking the 7 points? Then play them straight-up and make more than 2-1 on your money. Does your gut tell you that Troy Polamalu will intercept a Kurt Warner pass? You can wager on that, too.» —“Super Bowl 43: Prop betting sheet” Sporting News Jan. 28, 2009. (source: Double-Tongued Dictionary)
Further reading
juicy noun. A person who illicitly carries alcohol in a water bottle. «Gwen Alexander, who’s been working at the Astoria pool for two years, confirms there haven’t been any issues with fighting this year but she said rule enforcement is...
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short for “proposition”…
http://en.wikipedia.org/wiki/Proposition_bet
More citations for “prop(osition) bet” here.