House Party is the episode in which Screech's parents are going away for a few days to visit Graceland. Zack, Slater, & Screech decide to have some "guy time" since Screech's mother won't allow parties or girls at his house while she's away. However, the girls come over and accidentally break Screech's mother's prized bust of Elvis. The rest of the show is about all they went through in order to get a new statue before Screech's mother got home.
The Prom is the episode where Zack and Slater demand that Kelly finally choose between them. She chooses Zack, but then her dad loses his job and she can't afford to go to the prom. Jessie and Slater go to the prom together. Zack arranges a very special "prom" for just Kelly and him.
