Smoke wafting from a Cadillac Escalade on the Las Vegas Strip set off Paris Hilton's latest legal troubles when a motorcycle officer who suspected the smell was marijuana stopped the vehicle and police say a bag of cocaine later fell out of the 29-year-old socialite's purse. It's the second time this year Hilton has been arrested on drug possession allegations, although authorities in South Africa dropped marijuana charges earlier this summer. In 2007, Hilton pleaded no contest to alcohol-related reckless driving and was sentenced to 45 days in jail. This time, the hotel heiress was with her boyfriend, Las Vegas nightclub mogul Cy Waits, who manages a club inside the Wynn Las Vegas and was driving the black SUV that the officer stopped nearby at 11:22 P.M. local time Friday. The officer “followed the vapor trail and the odor of marijuana to the Escalade,” police Sgt. John Sheahan said. As other police arrived and a crowd gathered on the busy neon-lit Strip, Hilton asked to go into the Wynn resort for privacy, Sheahan said. “Miss Hilton pulled out a tube of lip balm,” Sheahan said. “At the same time ... a bindle of cocaine in a plastic bag came out of her purse” in plain view of police in the room.