crap shoot, n.
Etymology: < crap n.4 + shoot n.1
1. A game of craps (cf. craps n. a).
2. figurative. A situation or undertaking regarded as uncertain, risky, or unpredictable.
1958 N.Y. Herald Tribune 20 July a10/7 TV is the biggest crap shoot in the world—but it can pay off big, too.
1980 New Mexican (Santa Fe) 3 Jan. d5/6 I laugh at the predictors... It's a crap shoot, and always will be.
1992 B. Tropp China Moon Cookbk. 202 When buying fish, one can feel safe dealing with a trusted purveyor, but beyond that it's a bit of a crapshoot.
2010 Nanaimo (Brit. Columbia) Daily News (Nexis) 7 Aug. b3 The 2011 Grey Cup game will be played there on Nov. 27 but the timing of anything before that is a crap shoot at the moment.