VIDEO: Megan Mullally Dishes on Co-Stars, Talks Stage Show 'Karen the Musical' on WATCH WHAT HAPPENS!

On last night's WATCH WHAT HAPPENS LIVE, Andy Cohen gave IT'S ONLY A PLAY's Megan Mullally the names of some of her former co-stars, whom she must assign a show tune fitting of their personalities in a game called 'Mul-Lullaby of Broadway.' Later, Mullally dishes on the downfall of the ill-fated idea for "Karen the Musical," involving her famous "Will & Grace" character, Karen Walker. The actress reveals that Book of Mormon's Casey Nicholaw was set to direct and choreograph the show!

Check out the clips below!

Previews of IT'S ONLY A PLAY began Thursday, August 28, 2014. The show officially opened on Thursday, October 9th at Broadway's Gerald Schoenfeld Theatre (236 West 45th Street).

Academy Award winner F. Murray Abraham, Tony Award winner Matthew Broderick, Emmy and Tony Award winner Stockard Channing, international film sensation Rupert Grint, Tony Award winnerNathan Lane, Emmy Award winner Megan Mullally, and newcomer Micah Stock star in IT'S ONLY A PLAY. Three-time Tony Award winner Jack O'Brien directs.

In IT'S ONLY A PLAY, it's opening night of Peter Austin's (Broderick) new play as he anxiously awaits to see if his show is a hit. With his career on the line, he shares his big First Night with his best friend, a television star (Lane), his fledgling producer (Mullally), his erratic leading lady (Channing), his wunderkind director (Grint), an infamous drama critic (Abraham), and a fresh-off-the-bus coat check attendant (Stock) on his first night in Manhattan. It's alternately raucous, ridiculous and tender -- and proves that sometimes the biggest laughs happen offstage.

Photo by: Charles Sykes/Bravo