J.D. and Danni break up while Sean and Elliot plan to move in together; Carla gets anxious over last minute wedding plans; Dr. Cox bets Kelso that no healthy pastient will sign up for a full body CAT scan.. until Mr. Corman the hypochondriac (Richard Kind) returns.  J.D. ends up admitting his feelings to Elliot, prompting her to break up with Sean, only for him to realize he wanted what he couldn't have.