A sex act in which one partner sneaks into the other's room and gives them a blowjob while they sleep, usually waking them. (The recipient must ask for/consent to this in advance)
I was sound asleep when all of a sudden I was woken with a sneakybeej.
When two guys are receiving head in the same room and the persons giving the head switch so that the guys are getting head from the girl who was previously giving head to the guy next to him.
Stew was getting head while his friend Oliver was getting head next to him. Stew said to the girls, "Yo, lemme get that switch-a-beej!" And the girls said, "okay," and switched places.