A girl at a bar or other drinking establishment who you think you're getting somewhere with, but things unceremoniously end, leaving you alone for the night.
Ron: "Dude, that girl turned out to be a real Cul De Sac. I thought I was getting somewhere and then I just had to turn around."
Tom: "That sucks, bro."
Tom: "That sucks, bro."
by Rak Shade July 05, 2013