Fresh from leading the Cannes film festival jury, Robert De Niro (photo) found himself on stage at the Guys Choice Awards praising Keith Richards’ “big brass balls” and telling an audience that Sean Penn peaked with “Fast Times at Ridgemont High.” De Niro played the dirty-mouthed elder statesman at Saturday night’s Spike TV honors. Justin Timberlake leered at his “Friends With Benefits” co-star Mila Kunis as she took the “Holy Grail of Hot” trophy, while his “Bad Teacher” co-star Cameron Diaz kicked off the show with a monologue. “Mr. Popper’s Penguins” star Jim Carrey shared an unprintable story about how he became a funnyman through a painful encounter with an uncle. Richards took the night’s final honor, a lifetime achievement trophy previously given to the likes of Clint Eastwood. He hoisted the Brass Balls award, which resembles a giant dumbbell with spheres on two sides. Penn led a “Fast Times” reunion onstage, joined by Forest Whitaker, Judge Reinhold and other cast members from the 1982 film that launched his career. Mark Wahlberg was named “Guy of the Year” and his Oscar-nominated “The Fighter” took “Guy Movie of the Year.” … Larry Hagman, who played the cold, conniving oil baron J.R. Ewing on the beloved 1980s series “Dallas,” auctioned off many of his personal valuables Saturday in Beverly Hills. Caroline Galloway of Julien’s Auctions said a silver saddle was the priciest item sold, fetching $80,000. A replica bottle from “I Dream of Jeannie” brought in more than $10,000. The 79-year-old Hagman put in an appearance, describing items to the crowd then sitting in the audience during bidding. The collection brought in more than $500,000.