Green’s Dictionary of Slang

pertaining to those with whom one associates regularly.

1968		N. Heard Howard Street 29: He would find Hip drunk, standing on the corner with his equally drunk hangout partners.
1995		(con. 1985–90) P. Bourjois In Search of Respect 105: Primo cultivated a large hang-out crowd to fulfil a psychological need for power and domination.
2001		S. King Dreamcatcher 6: The Beav is basically a happy guy, any of his hang-out buddies would tell you that.