Urkel is invited to stay with the Winslows when the nerd's parents go out of town ... and quickly causes plenty of chaos. He drives Laura's study partner away, convinces Richie to get into a fight with a preschool bully, and accidentally vacuums up Lt. Murtaugh's fish that Carl was baby-sitting.

Eddie takes his pranks on Laura too far by inviting her ex-boyfriends over to the house whenever Stefan is around. Laura decides to fight fire with fire by conning Steve into helping her get even with her dim-witted brother. She uses his black book, which contains phone numbers of Eddie's previous girlfriends, and invites them over on his birthday. When he and Greta arrive to his birthday party to see his ex-girlfriends, they are incensed by the whole thing. Finally, Steve sets both Eddie and Laura straight on how ungrateful they were to have each other. Steve admits that he was always jealous of them because his parents never loved him and that the Winslows were like his own family. Both siblings apologize soon after. Meanwhile, Commissioner Geiss learns a lesson that sometimes it's better if a more experienced cop, like Carl, is promoted to captain over an inexperienced cop, like his son.