Green’s Dictionary of Slang

(rap music) the bassdrum from a Roland TR-808 drum machine, which is a popular make; cite 2005 (1) indicates the sound produced.

2001		Source Aug. 100: Bass is up-tempo, 808-driven music.
2005		B. Coleman Rakim Told Me 14: Saddle shoes make a great 808 on a parquet floor.
2005		B. Coleman Rakim Told Me 65: ‘Patrick [Adams, a recording engineer] was the guy who first turned me on to the 808’ .