Benny is too shy to ask a girl out on a date, so to help him out, Alan asks Karen Frankel, a classmate Benny has always liked, to a couples-only party, and asks Katie to go with Benny, then they will "trade" later on. But Benny develops a crush on Katie and Alan learns that Karen has had a crush on him for years. Meanwhile Sophie and Phyllis help organize a rummage sale which honors the fallen son of a neighbor in aid of a veterans' hospital, while George invests in one of the new Polaroid cameras.

Benny tells Alan that Katie is now his girlfriend and they can't be friends any longer; meanwhile, Karen Frankel further misunderstands her relationship with Alan, and, during preparations for the rummage sale, Aunt Sylvia and Sid seem to be hitting it off.

Katie finally explains her feelings to Benny and eventually he and Alan resolve their differences--after he makes peace with Karen and Benny has a heart-to-heart with Grandma. Meanwhile, the rummage sale wildly achieves its goal, and Sid invites Aunt Sylvia back to the store for champagne.