“This is really gross,” the Zero Dark Thirty actress warned in the understatement of the year.

Jessica Chastainhas something to get off her chest.

“I can say it now, ‘cause we’re closed.

A Doll’s House with Jessica Chastain

Jessica Chastain in ‘A Doll’s House’ on Broadway.Courtesy of A Doll’s House

This is really gross, what I’m gonna tell you guys,” Chastain warned.

“I threw up.

I threw up and I swallowed it.

And no one knew!”

It was a nightmare and I couldn’t explain," Chastain said.