Host James Lipton asked Gyllenhaal about how he and Ledger prepared for their Oscar-nominated roles in Ang Lee's story of two men who fall in love in the Wyoming mountains, and whether the two worked on establishing a relationship before cameras rolled.
"Heath and I knew each other for years before ['Brokeback'] because we had both auditioned for 'Moulin Rouge' together," Gyllenhaal said.
Gyllenhaal then launched into a profanity-riddled impression of the late actor, complete with Aussie accent.
"I remember thinking, 'I like this guy,'" Gyllenhaal recalled with a laugh, adding that Ledger was "super lovable."
Despite that lovability, Gyllenhaal admits that he was surprised when Lee chose Ledger for the film. Still, the pair made it work, and their electric onscreen chemistry fueled rumors of an off-screen romance, which Gyllenhaal politely denied.
"It's a huge compliment," Gyllenhaal told Lipton, but he's straight. His biggest turn-ons? "Tits and ass," he told the host.
For more from Gyllenhaal, check out the entire segment, which airs Thursday at 8 p.m. on Bravo.
[h/t The Wrap]