Neither be ye idolaters (μηδε ειδωλολατρα γινεσθε). Literally, stop becoming idolaters, implying that some of them had already begun to be. The word ειδωλολατρης seems to be a Christian formation to describe the Christian view. Eating τα ειδωλοθυτα might become a stepping-stone to idolatry in some instances.

Drink (πειν). Short form for πιειν, sometimes even πιν occurs (Robertson, Grammar, p. 204).

To play (παιζειν). This old verb to play like a child occurs nowhere else in the N.T., but is common in the LXX and it is quoted here from Exodus 32:6. In idolatrous festivals like that witnessed by Moses when he saw the people singing and dancing around the golden calf (Exodus 32:18).