1 Corinthians 10:7

Neither be ye idolaters, as were some of them; as it is written, The people sat down to eat and drink, and rose up to play.

'Neither be ye idolaters' -'Lit., stop becoming idolaters, implying that some of them had already begun to be.' (Robertson pp.152-153)

'as it is written'. Exodus 2:4. The infamous "Golden Calf" incident.

'The people sat down to eat and drink, and rose up to play' -Paul fixes his attention, not on the construction of the calf, but on the "feast" which attended the worship of it.

The Corinthian's were not arguing for the right to construct or worship idols, rather, simply for the right to attend the feasts in the various idol temples. In response, Paul cites the worship of the golden calf, and labels as "idolatry", the feast which attended it's worship. The eating and drinking in presence and or honor of the idol was "idolatry" too!

'The eating of the cultic meal constituted idolatry just as it did at Corinth. Although neither the Israelites nor the Corinthians considered their conduct to be idolatrous, both were guilty of it.' (Willis p. 323)

'rose up to play' -'often refers to cultic dancing..and in the Exodus narrative the revelry is further expressed in terms of "shouting" (1 Corinthians 32:17), "singing" (18), and "dancing" (19), nonetheless in this case..it almost certainly carries overtones of sexual play. This is suggested by the further description in v.25 of the people's "breaking loose", or "running wildly out of control".' (Fee pp. 454-455)