A finishing move where when you're about to cum when fucking a chick in her ass, you pull out your shit browned dick, stick it in her throat, then shoot it out likesteam from a steamboat.
I gave this chick a brown steamboat after she had diarrhea so her breath smelled like shit all night.
From military parachuting: when a parachute fails to open it's called a streamer, and if the jumper's reserve parachute doesn't function, the jumper's going to die- the brown in the phrase is either from the dried blood on the chute when the jumper assumes the consistency of rasberry jam, or from the well-known, first you say it, then you do it..."Oh, sh--!"
I thought sure that streamer was going to be a brown streamer until his reserve popped at the last second.