At the end of the sing "Look at Me, I'm Sandra Dee," Sandy walks in on the other girls mocking her. Rizzo simply replies, "Some people are so touchy," rather than trying to come up with a lie to spare Sandy's feelings. This seems very odd, unless you pay close attention to Rizzo's solo later on, "There are worse things I could do." One of the last lines is, "I don't steal, *and I don't lie.*" Making fun of Sandy wasn't beneath Rizzo, but lying to her was.
If you look at the lyrics of Summer Nights, it has the lyrics "Tell me more, tell me more, was it love at first sight? Tell me more tell me more, did she put up a fight?" The girls were asking Sandy whether she and Danny had sex, and whether Sandy fought back. That means... you guessed it..... rape
Actually, the girls just said the "at first sight" line, and the boys said the "fight" line, so they were unrelated lines that just happened to rhyme. It helps, but the boys' line still sounds...wrong...
Besides, in Danny's lines right before that one, he was telling his friends how he met Sandy when he saved her from drowning - and people who are drowning often panic and struggle to keep themselves afloat, which ends up hindering their rescuers. They could have been asking about that.
Doubtful, as the "no means yes" double standard was quite common, along with the "madonna/whore" split - at least in male teen thought at the time. Consider some of the anti-STI public info films that ran at the time (50s).
A more benign interpretation (though hardly one without problems) is that they were asking (and thinking it would make the story more exciting) if she was Playing Hard to Get.