S3·E11 Don't You Know Anything About Women?

Kevin wants to take Susan Fisher to the dance, but she has a boyfriend, Donald Wallach. However, he hears rumors that they have broken up, so he's about to ask her until Donald interferes. Linda Sloan, his lab partner, suggests that they go as friends so they do. They have a good time in the beginning, but it turns sour when while Linda is dancing with Steve Padway, Kevin dances with Susan and they have punch. How is it bad? Susan leaves and Linda comes back and asks if they half-filled cup of punch that Susan left is for her, but Kevin says that it's Susan's in a not-so-nice sort of way. That basically breaks Linda's heart and she leaves. Kevin is about to ask Susan to dance again but she's dancing with Donald, so Kevin leaves, not knowing that Winnie came in, probably looking for him.