Green’s Dictionary of Slang

1. to play around, to mess about; thus grab-assing n., fooling around.

1967		(con. 1920s) J. Thompson South of Heaven (1994) 169: Everyone seemed to be grab-assing.
1974		C. Loken Come Monday Morning 20: Least it made them stop their grab-assin’ an’ look over his way.
1977		L. Heinemann Close Quarters (1987) 153: We was a little smoked and grab-assed and poked around and fucked around.
1986		L. Heinemann Paco’s Story (1987) 25: The conscientious objector fumbled and grab-assed [...] and generally made such a muddle of it.
1993		S. King Dolores Claiborne 87: All of em laughin and grab-assin around and maybe passin a bottle of cheap wine in a paper bag.

2. to make physical advances, to grope or flirt.

1953		J. Thompson Savage Night (1991) 58: I’d got to grab-assing around with Fay Winroy.
1969		P. Theroux Murder in Mount Holly (1999) 35: They had bowled together, had dime-beers together, grabbed ass together.
1990		S. Morgan Homeboy 29: Baby Jewels gladhanding politicos, grabassing showgirls, squeezed into nightclub booths with minor celebrities.
2000		J. Bouton Ball Four—the Final PItch 497: Ballroom is not your basic grab-ass dancing, but moving-across-the-floor dancing.
2001		J. Stahl Plainclothes Naked (2002) 4: Till he bought mall at ninety, Pop Lee [...] still liked to grab ass and talk nasty.