Wiktionary
n. (context slang English) horseplay; play fighting, wrestling. Any sort of playful or casual activity that might be mistaken for fighting.
Usage examples of "grabass".
Lesson one for the old man trying to play grabass with (what the nuisance bitchily calls) "young stuff" (when she's trying to bug me): they don't do it that way these days.
And what she wants is to play grabass with cute guys who show up in her office at the end of the day.
Next time you see your pal the president, tell him to stop playing grabass with me every time I’m alone with him in the Oval Office, okay?
Mikey, when a man gets turned down by a woman and then waits until she's asleep and jumps on her and tries to hold her down long enough for to get his wang into her, that's not just horsing around and playing grabass, man, that's what they call forcible rape.