1. n. A fecalated and arrogant musician, particularly one who is a middle-aged, pretentious, artsy narcissist who fucks a musical instrument and claims to be too busy and important to take the time to wipe his own ass. Since he has no friends, the ass is never wiped; therefore his bottoms remain perpetually brown.
2. n. The soiled pants or underwear of a brownbottoms.
3. v. to insert the bow of a cello, violin, or viola de gamba up one's ass without cleaning it before its musical usage is resumed.
That virtouoso of the cello is a real brownbottoms.
Don't go near him; his brownbottoms will make you wretch and gag.
Ewww, don't touch that instrument--I think some one brownbottomsed it!