Barbara Crampton and Kathleen Kinmont appeared together for all their screen time which was about ten minutes, five of which took place when they were in bikinis, topless, completely naked or briefly showing off their buttocks for the mooning scene. In fact most of their dialogue took place when they were in their bikinis, topless and then completely naked.
Fraternity Vacation was the first movie in which Kathleen Kinmont appeared nude. Perhaps as a bit of handholding it was agreed that Kathleen Kinmont would take off Barbara Crampton's bikini first, as Barbara Crampton had done nude scenes before, and then the now topless Barbara Crampton would take off Kathleen Kinmont's bikini.
In contrast to Kathleen Kinmont giving Cameron Dye a full-on kiss, Tim Robbins and Barbara Crampton avoided kissing each other on the lips before Barbara Crampton as Chrissie asked Kathleen Kinmont as Marianne to take off her bikini.