Robert Downey, Jr. and Ben Stiller took the stage last night at Koi in Planet Hollywood in Las Vegas and proceeded to gently, then not so gently, roast each other. A moment after Stiller taunted Downey, Jr. over an award he was receiving (Male Star of the Year, part of the ShoWest exhibitors' convention that had brought them to town for a preview of their film together, Tropic Thunder), asking, "Is that an adult film thing?" the sometimes-troubled actor riposted with a dig at Stiller's unloved Heartbreak Kid and Mystery Men misfires.

"You must have been in jail when it came out," explained Stiller, drawing a loud chorus of "ooooooowhoaaao" from the crowd of two-hundred plus film execs and exhibitors.

Downey, Jr. the picture of health in a short haircut and light beard, chose to abide the quip with an indulgent smile. (They were killing in the room, and clearly actors doing comedy will kill at any personal cost.)

The trailer and selected footage they showed went also went down to good effect, with director Stiller playing a particular kind of stud actor in ego conflict with Downey's character, a deeply methody Australian star in blackface and Afro-ized hair playing a black soldier. At one stage, selling a particularly gross bit, Stiller's character caps a debate by reminding his co-stars that he's done "a lot more effects-driven tent pole movies than you", and knows a latex decapitated head when he sees one.

Downey, Jr. and Stiller repaired to the balcony and continued running the dozens on each other for Portfolio.com, Downey accusing Stiller of abusing the cast via bullhorn and making him sweat off his laboriously applied makeup with repeated 200-yard rehearsal sprints runs through the jungle shrubbery on Kauai.

Stiller sparred back for a moment before giving in and punching the praise button to say with sincerity it was all he could do perform his scenes opposite the outlandishly gifted Downey--"I was seriously intimidated, because I didn't know him really." (His co-star stared at him with humble skepticism before paying tribute to Stiller's dedication in shunting his own close-ups to the end of the company's 14-hour days, when all parties could hardly be at their best.) The love fest was an interesting tangent from Stiller's earlier contention that his kid had dubbed him a quadruple threat whereas Downey was limited to just "Acting, acting, acting.", and that his kid actually sees him as a superhero. That, Downey had said with rich condescension, isn't the same as "an actual franchise"--obviously referencing Iron Man, which, as Paramount executive Rob Moore pointed out, is part of a dauntingly strong upcoming Paramount slate that includes a revitalized Indiana Jones, Kung Fu Panda, and The Love Guru.

The latter movie had been introduced to the exhibitors via a surprise visit by Mike Myers as DreamWorks animation topper Jeffrey Katzenberg was kvelling about the panda movie (earlier in the day he'd given a much-noticed presentation about the technology-advancing 3D presentation, Monsters vs. Aliens". After admiring Katzenberg's butt and noting, " I've got a man crush,") Myers showed selected scenes from the guru film which appears to be long on funny Myers-style sketches but must await a fuller assessment when it's stitched together.

All in all as the crowd was reminded when Katzenberg recalled the introduction seven years before of Shrek "on this exact day" (the convention's Tuesday night), that Paramount is very capable of putting down some pretty big footprints. In a way that's as showbiz-savvy as any major in town--whether that town is Hollywood or Las Vegas.

Other coming highlights include product reels from Universal and Warner Bros., the premiere of Sony's gambling-themed 21, and the closing night ceremony that will honor Downey alongside Female Star of the Year Anne Hathaway (to be seen opposite Steve Carrell in Warner Bros.'s Get Smart) and Director of the Year Christopher Nolan (whose Batman Begins, with a performance by Heath Ledger that's already building to legendary status, will be previewed here). Meanwhile, somebody should tell Jack Black he was missed as Stiller and Downey grumbled about handling the promotional chores themselves, wondered if his non-appearance here was the result of a busy schedule, and finally settled on Stiller's blithely voiced aside: "F**k him."

(Ben Stiller and Robert Downey, Jr. on Tuesday night in Las Vegas; photo by Alex Berlinr/BEI)