short for cock bloker. Someone that gets between your cock and a lady you want to give it to. Thus preventing your cock from reaching its intended target.
Dude 1: Dude this girl sucked on my C&B last night!
Dude 2: Dude ur what????
Dude 1: My fuckingCOCK and BALLS!!!
Dude 2: Dude thats fucking sweeeet!
Dude 1: I Know! It was tight.