Margaret O'Keefe, Cliff's mail carrier girlfriend living in Canada, has come back to Boston wanting to rekindle her relationship with Cliff. Cliff also wants to do so, but he isn't thinking marriage just yet. The biggest hurdle in the relationship is that Ma Clavin and Margaret have never met. When Cliff tells Ma about Margaret, Ma is hurt - she feels like Cliff wants to replace her with another woman. But Ma and Margaret do meet, and after an initial coolness between them, Ma and Margaret get along famously. They get along so well that Ma proposes to Margaret for Cliff and Margaret accepts, without Cliff even being there. Ma and Margaret announce this news to the gang at the bar, but Cliff doesn't yet want to get married. He will have to tell both Margaret and Ma, the latter who may be the more difficult person to tell. In doing so, Cliff and Ma demonstrate who wears the pants in the Clavin household. Meanwhile, Rebecca and Sam are still trying to have a baby. It's been two months without success. Rebecca is being scientific about it, and thinks the problem is that Sam is too warm "down there" due to the fact that he wears constricting bikini briefs. She suggests he try boxer shorts that contain freon to freeze his testes, which is what he becomes.
- Sam is growing a little exasperated as Rebecca feels that he is the reason why the two have not been able to conceive. Her strict rules about not drinking coffee and even wearing cold-insulated boxers don't help either.
Meanwhile, Cliff has gotten word that his former girlfriend, Margaret O'Keefe, is visiting from Canada. Cliff brings his Ma to Cheers to meet Margaret. At first, Ma puts on a dramatic 'woe is me' demeanor, but once she and Margaret get talking, the two end up getting along just fine.
This all sits nice and well with Cliff...until Ma pretty much decides that Cliff and Margaret are to be wed!
The two seem happy about this, but Cliff quickly takes Frasier aside, and tells him that even though he cares for Margaret, he does not like the fact that his Ma is pushing him into this. Frasier then tells Cliff that he should stand up to Ma, and tell her what he thinks.
Cliff then tells Margaret that they will get married when the time is right, before telling Ma that he and Margaret will make their own decisions. However, his brash attempt to carry her out of the bar ends up chipping her tooth, and leaving them in a crumpled heap at the bottom of the stairs.
Ma throws up her hands, and helps carry Margaret's body up the stairs, calling down to Cliff that she'll be back for him later.