• Share
  • Tweet
  • Share

We know you are dying to know whether Robert Pattinson prefers boxers or briefs.

And since Kristen Stewart isn't one to kiss and tell, leave it to funny lady Ellen DeGeneres to get the dirty deets from Rob.

During an interview on The Ellen DeGeneres Show airing this afternoon, Rob told Ellen why she is an integral part of his daily underwear choice...

"I save your ones [Ellen underwear] for special occasions," Rob reveals on the show today.

"I was doing the last Twilight movie, and I only had one pair left and they were those ones," Rob dished to Ellen while laughing. "We were doing this big fight scene and for some reason, I think the shape of my body, my back is too long or something, my ass is constantly hanging out."

When Ellen asks Rob why his tush is always on display, Rob reveals he may be even more of a freak of nature than we initially thought.

"I genuinely think I have a few too many extra vertebrae or something," Rob joked. "We were doing this big fight and every shot has these Ellen underpants. It came to a point where producers are calling up my agent going, ‘I don't know what he is up to, but I don't like it.'"

Someone who doesn't like R.Pattz? Hard to believe.

"They never questioned Fruit of the Loom before," Rob joked.

And with that, Ellen gives Rob a basket full of Ellen underwear.

But one of the most interesting pieces of news Rob shared with Ellen: "I don't know how to use a washing machine."

Um, ew? Looks like we will be seeing a lot more of those Ellen undies peeking out of Rob's pants!

Funny, we took R.Pattz for more of a free-fallin' kinda guy.

WATCH: Rob at the Water for Elephants premiere