Green’s Dictionary of Slang

(US) committed to enjoying oneself.

1973		L. Bangs in Psychotic Reactions (1988) 114: I betcha when he’s not being a Sensitive Genius he’s a getdown dude who don’t give a shit about nothin’.
1994		(con. late 1960s) R. Crumb Zap Comix 13 in Coffee Table Art Book (1997) 32: Man, this new side by the ‘Stones’ is a funky get down stone groove!!