blast cap
When a girl gives a guy a handjob (or a guy gives a guy a handjob, I don't give a fuck) and she puts her mouth over his dick just as he comes to avoid a mess.
Example:
DudeBro 1: Yeah she was jerkin' me and then I came all up in that bitch
DudeBro 2: Oh dudeguy she gave you the blast cap eh? NICE 1 BRO DOG
DudeBro 1: Yeah she was jerkin' me and then I came all up in that bitch
DudeBro 2: Oh dudeguy she gave you the blast cap eh? NICE 1 BRO DOG