The Jimmy Castor Bunch created a song that is one of the all time funk hip-hop classics, and probably played more often at any break dance battle or authentic hip-hop party than any other song hands down. Not to mention how often it's been sampled! You may not have heard the whole thing, but even if you've seen the most mediocre hip-hop video you've seen some kids getting down to this classic B-Boy break beat of all break beats. Check this live TV appearance from 1972 of the original song "It's Just Begun" (from the album 16 Slabs of Funk) in it's entirety.
and here's the studio version: