Season 3: Episode 55: Wife Swapping
Since her doctor put her on bedrest for the week, Kim is in a bind when her babysitter calls and cancels. So Christine offers up Jimmy's babysitting services. Greg and Christine both have to go to the store to pick up stuff for Kim and Jimmy, respectively, so Jimmy recommends they both go together, even though they don't want to. Greg and Christine end up having a surprisingly good time out at the supermarket -- where Greg gets to buy the bread Kim won't let him buy -- that they cap it off with a trip to a coffee shop where Jimmy refuses to go. Kim and Jimmy, who had a bad time together, become jealous when they find out how much fun their spouses had -- and that they're planning to go out again. Greg and Christine are equally jealous when they come back from their second night out to find Jimmy giving Kim a neck rub in her bed. Jimmy and Kim decide to get even with them by pretending they're pals too. But the pair can't keep the facade up after a game of Scrabble gone awry, and blast their spouses for having fun. That's when it comes out that Greg and Christine are sick of each other's company.