America's sweetheart has a temper!

In the November issue of ELLE, Jennifer Aniston (who directs a short film in Lifetime's Five project) admits she once lost it on set with a male director -- and it got physical!

"I threw a chair at a director. It wasn't my proudest moment," the Horrible Bosses star, 42, admits.

But the outburst had nothing to do with Aniston's own ego or on-set demands. She explains: "He was treating a script supervisor horribly… When the director walked in, I threw a chair at him."

Good thing her aim wasn't so hot. "I missed, of course. I was like, 'You can’t speak to people like that.' I can't tolerate it.”

Aniston, who has appeared in dozens of films in addition to her smash TV show friends, declined to name which director set her off.