Maybe this is what's causing problems between Jake Gyllenhaal and Reese Witherspoon.
Gyllenhaal has been in Pittsburgh shooting steamy love scenes with Anne Hathaway for his newest flick, "Love and Other Drugs" (out next year).
"We've been baring almost all of us," he said on "Jimmy Kimmel Live" Thursday night. "So that's not been bad either."
Continued Gyllenhaal, who is currently starring in drama "Brothers," "We're pretty naked except for a merkin."
What's a merkin?
"Fake pubic hair," he explained. "It's like a cover for your junk!"
Hathaway is donning "a similar sort of thing," Gyllenhaal added. "But it has other functions."
Said Kimmel, "And you're getting paid to do this?"
"Well!" Gyllenhaal responded.
The actor also showed off his new tattoo on the show: a Pittsburgh Steelers logo on his back.
"I love Pittsburgh. It's fantastic!" he enthused. "I've been to two Steelers games."
(Quite a different feeling than Sienna Miller has for the city. In 2006, she called the Pennsylvania town 'S-itsburgh' in Rolling Stone.)