It's obvious that their film, The Bounty Hunter, benefits greatly from speculation about the pair's romantic involvement (and can use every bit of it, reviews say).
But is it all for show, or is there something there? Rumors flew once again after Butler was caught playing grab-ass with Jen while greeting fans in Paris, France.
In a Friday interview, Butler joked about his booty bust.
"I'm a bit of a bad boy," the notorious playboy actor admitted, before demurring, "by the way, I'm still not sure my hand was really on her butt. I think that's just the way the camera was angled ... I actually haven't seen [the photo]."
FRIENDS AND (MAYBE) THEN SOME: Where's the other hand, G?
"If I was going out with Jennifer, I'd be more than happy to say I'm going out with Jennifer, but it's just not true," he added after being pressed further on it.
Yet a Butler pal counters that the flirty costars have been "hooking up for a while," even if they're not an official couple. So it's that sort of arrangement. HOT!
An Aniston pal confirms that they slept together in Mexico at her February birthday blowout: "She would like it to be more, [but] they're friends with benefits."
Damn, Jen. You can't give away the cow when ... forget it. A rep for Aniston, meanwhile, says the "friends with benefits" label is "both crude and incorrect."
So basically ... no one knows. Probably just how they like it.