Slang for a low brass section, usually of a marching band. Named after the euphoniums, trombones and baritones. Characterized as being very obnoxious and rebellious, yet just funny or likable enough to somehow get away with it...usually. Both hated and loved by members of the rest of the band.
"Where are the euphonabonatones?" "I dunno, probably off harrassing the clarinets. They say they're 'bonding'."
While other sections were practicing the opener (like they should), the euphonabonatones were too busy marching in the shape of a dick.