bumping, n. — Green’s Dictionary of Slang

bumping n.

[the ‘bumps’ come from the thud of the bass, which will be turned up high]

1. (US black teen) the sound of a car stereo; the act of playing (music) loudly.

1987		King Tee & Mixmaster Spade ‘Ya Better Bring a Gun’ 🎵 You got your sounds bumpin, playin Zapp and Vibe.
1992		Ice-T ‘Cop Killer’ 🎵 I got the stereo bumping.
1998		M. Ferguson ‘Unstoppable Sl.’ in Columbia Missourian 19 Oct. 1A; 8A: bumping – blasting music.

2. (US black) having an uproariously good time.

1994