Why does a heterosexual man swallow the sperm of another man after he has given him a brojob?
Because of the cream filling inside, just like the individually wrapped cakes of Hostess Twinkies.
Twinkie Filling
Explanation
This is a vulgar joke that uses a comparison of semen to the cream filling of a Twinkie to explain why a man would swallow another man's sperm after a brojob.