POTTY TRAINING – A disgusted Martin challenges Frasier and Niles to fix a "running" toilet instead of calling a plumber, but their efforts go down the drain. When the two plumbers – brothers Danny (guest star John C. McGinley) and Billy (guest star Mike Starr) – arrive, Frasier and Niles recognise them as the junior high bullies who used to try to flush Frasier and Niles' heads in the toilet.
- John C. McGinley as Danny Kriezel
- Mike Starr as Billy Kriezel
- Macaulay Culkin as Elliott (caller)