“Real Housewives of New York City” stars Kelly Bensimon and Ramona Singer had a catfight over fellow reality star Khloe Kardashian at nightclub Quo. The housewives refused to talk or be photographed with each other when they arrived at the launch of Three Olive Vodka flavor RangTang on Tuesday night. But after spying Bensimon sitting and chatting with Kardashian, Singer “pounced like a tiger,” our source said. “Suddenly there was a ruckus. Ramona barged her way through the VIP area and practically jumped over a table to get to Khloe, and tried to sit between her and Kelly, who was mortified and left immediately.” Singer’s rep said, “Ramona did not steamroller her way in — Khloe invited her. They chatted and they took a picture together.” Others watching the drama included Dina Lohan and MTV’s Adrienne Bailon. Porn legend Ron Jeremy missed the action as he was grinding with a “middle-aged” woman on the dance floor. Bensimon declined to comment.