Debra Messing tells ET's Kevin Frazier why Christmas is scary!

In her new Christmas comedy 'Nothing Like the Holidays,' Debra plays a high-powered executive who would rather raise capital than a kid. Christmas gets scary for her when her husband Mauricio (John Leguizamo) takes her to his parents' home for the holidays and she meets her mother-in-law, who is dreaming of grandchildren.

"Going home for the holidays is scary for everybody, whether or not you're in the family or you're outside of the family -- it's scary," Debra tells Kevin.

In real life, Debra and her husband, Daniel Zelman, are the parents of four-year-old son Roman, but even so, "The Starter Wife" star says she knows what it feels like to be an outlaw around her in-laws!

"I just didn't know their customs," Debra admits. "So when I walked in their kitchen and I saw a hen in the sink, I thought, 'I don't know what to do with that.' They had their own little games that involved potatoes and poems and you just hope you will survive it."

Debra jokes that she gained 10 pounds over the course of the film, which took five weeks to shoot, but she loved the dinner scenes because they were fun, in addition to being fattening!

"It was all this Puerto Rican food that essentially everything, no matter what was done to it, always ended up being put in a vat of fat. So everything was dripping with oil and it was like beans and animals I didn't even know about. We had to sit there and eat for like 18 hours," she reveals.

'Nothing Like the Holidays' opens in theaters on December 12.