Shelley Long and Mark Steines dish the dirt on DeDe, the role Shelley plays on "Modern Family," who just happens to be the ex-wife of Ed O'Neill's character, Jay Pritchett -- who is not too popular!

DeDe drops in for a surprise visit and is determined to make amends with everyone she offended during what has been deemed "the incident" at Jay and Gloria's (Sofia Vergara) wedding.

"I ruined her wedding," Shelley tells Mark. "And I kind of make it worse every time I try to apologize."

Needless to say, no one is thrilled to see her, and everything comes to a head when the whole family shows up to dinner at Claire's (Julie Bowen) house. Shelley goes for the throat and ends up down for the count as she battles her ex-husband's new wife.

"So the fight starts all over again," Ed says.

The former "Married … with Children" star also tells Mark that he almost worked with Shelley earlier in his career on "Cheers."

"I was being considered for the part of Sam Malone," he shares.

"I was never aware of that," Shelley says, "But I love him. I love him."

Shelley's episode of "Modern Family" airs tonight at 9 p.m. on ABC.