Signing up for shared housing sight unseen, especially in a college or university setting. You may be assigned a roomate from hell or you may get someone pretty sweet. Many feel the risk is too high so they seek alternative housing sources. Term derived from the game Russian Roulette where a bullet is placed in the chamber of a revolver and placed up to ones head. You may luck out, but most dont think its worth the risk.
"Fuck that shit, last time I got assigned a roomate, he was an anal-retentive dork who played Halo all day and cock-blocked left and right. I ain't going to play roommate roulette this year, I am going to money up and get a studio."