This is not only an early King Of The Hill episode, but one of the first ones I ever saw, at about midnight in a hotel in summer 2008. Let me just say that seeing it again this year was so awesome. Season 1 KOTH has a bizarre, washed out feel that clearly shows how old it is (my sister was like, "when was this made??"); even two of the house room have completely different colors!
Anyways, Joseph invites Bobby to his birthday which will have girls at it. Bobby is all nervous about it and practices being a boyfriend with a plastic head Luanne is using for practicing her desired job of cutting hair. Hank, of course, is uncomfortable with it and puts it away, and later destroys it! But then, on the day of the party, Connie gives Bobby some confidence by kissing him! I won't ruin the ending, but I'll just say it's unlike any KOTH ending you've ever seen!