A sexual act involving flatulence. It usually involves five or more people (usually men) bent over with their pants off ("the harmonica") and one person of any gender ("the player"). "The player" kneels behind the first person, places his or her lips on the anus, forming as tight a seal as possible, and allows the person to blow a fart into his or her mouth. "The player" takes the fart in his or her mouth, places his or her lips on the second anus in a similar fashion, and forces the fart into that person's rectum. The fart is promptly blown back into "the player's" mouth, who continues this action down the line, until every person has recieved/expelled the same fart (sometimes doubling back and forth several times).
EXAMPLE: "Dude, years ago, I was backstage at an N'SYNC concert, and Britney Spears was giving 'em the ol' Brown Harmonica!"
by JoeyKayComedian September 26, 2009