Green’s Dictionary of Slang

1. (orig. US black) a period of relaxation, relaxing.

1997		N. Barlay Curvy Lovebox 166: Like his whole day’s just been one big kickback before the comin’ of night.
2001		(con. 1975–6) E. Little Steel Toes 68: It’s kickback, they like born-again maniacs.

2. (US campus) a party, a social gathering.

2014

C. Eble (ed.) UNC-CH Campus Sl. Spring 2014 Fall 4: KICKBACK — social gathering.