Usual refererance used by gamers in online play Halo 2 and 3. The term refers to the action when two opposing players, one from the red team, and one from the blue team, are engauged in battle and punch or gunbutt eachother at the same time. This results in the so named Double Baby Cock Smash, or D.B.C.S.
The other team got lucky with that last D.B.C.S for the win.
Lucky noob got a Double Baby Cock Smash