Adam Clarke on Exodus 32:6

The people sat down to eat and to drink - The burnt-offerings were wholly consumed; the peace-offerings, when the blood bad been poured out, became the food of the priests, etc. When therefore the strictly religious part of these ceremonies was finished, the people sat down to eat of the peace-offerings, and this they did merely as the idolaters, eating and drinking to excess. And it appears they went much farther, for it is said they rose up to play, לצחק letsachek, a word of ominous import, which seems to imply here fornicating and adulterous intercourse; and in some countries the verb to play is still used precisely in this sense. In this sense the original is evidently used, Gen 39:14.