Flip-Flop: Part One is the fifteenth episode of the sixth season and 131st overall.
- Eric McCormack (Will Truman)
- Debra Messing (Grace Adler)
- Sean Hayes (Jack McFarland)
- Megan Mullally (Karen Walker)
- Shelley Morrison (Rosario Salazar)
- John Cleese (Lyle Finster)
- Minnie Driver (Lorraine Finster)
- Dave Foley (Stuart Lamarack)
- Eileen Brennan (Zandra)
- Karen and Lyle sing an impromptu version of "Something Good" from the musical film The Sound of Music (1961).
- Taboo the Boy George musical. Simply Red and Frankie Goes to Hollywood.
- Karen again insists that Lorraine is scared of toothbrushes because of the stereotype that British people have bad oral hygiene. She first implies this in Dames at Sea. Later she calls Lorraine "Lady McBreath" because of her acting.
- Jack and Karen tell a gender-confused version of the 1982 film An Officer and a Gentleman.
He's back, he's moved in, and we're shagging like two lieutenants after lights out. — Karen
The streets are really tough out there for a boy alone.
Ironically, they're tougher for two boys together. — Jack