Thursday night on "Friends," Christina Applegate is back as the big guest star, and Joey scores big laughs helping Monica and Chandler adopt a baby. But there's an even bigger twist to the Monica and Chandler baby story.

On "Will & Grace," Jack learns to spell, while Harry Connick Jr. spells out Leo's future with Grace for "Extra." He says, "I'm going to dump her, she's going to dump me, or I'm going to fall in love with either Will or Jack."

The big guest stars crashing Must-See Thursday continues on "Scrubs." Scott Foley is back, and on his back, as Sean. And the doctors look for a cure for the deadly love triangle.

You'll kick yourself if you miss Must-See Thursday on NBC.