Will (Eric McCormack) and Grace (Debra Messing) have been living together off and on for years, and even though Grace isn't a newcomer to the gay scene, she still doesn't know every term in The Gay Handbook™.

In an exclusive new clip from this week's episode, "Emergency Contact," Grace forces Will to "gaysplain" the term "Platinum-Star Gay" to her. For those of you who don't know, a "Gold-Star Gay" is a gay man who has never had sex with a woman—but a "Platinum-Star Gay," like Jack (Sean Hayes), is a gay man who has never even come in contact with a vagina because they were born via C-section.

The new episode is noteworthy not only because of Jack's reveal, but also because it's the return of Grace's ex-husband, Leo (Harry Connick Jr.), who Grace is surprised to learn is still her medical emergency contact. According to photos released from the episode, in addition to the return of Leo, Laura Kightlinger is also back as fan favorite sassy Nurse Sheila.

How does Grace handle her reunion with Leo and will Jack ever come in contact with a vagina? We are pretty sure we know the answer to the second question, but you will have to tune into Will & Grace this Thursday to find out what goes down when Leo comes back into Grace's life.

Watch the exclusive new clip below.