man walks into a bar and asks for 12 shots of ouzo 
bartender is busy pouring them and asks, "why 12 shots, wha's all this for?" 
man : "i'm celebrating my first blow job" 
bartender " well, congratulations! have one on the house!" 
man: "naw, if twelve won't get rid of the taste I dunno if an extra one will do any good!"