A sexual technique amongst gay males, where one will fellate the other until the male receiving fellatio ejaculates in the mouth of the other. The fellater then sneezes (with a mouth full of ejaculate) on the receiver, spraying him with his own semen. Afterwords, they yell "BOOMHEAD!" and share a high five.
Tony: I gave Francois some wikked BOOMHEAD last nite.
Joe: Get the hell away from me.