Lindsay Lohan is back to what she does best, partying late and falling over in public, according to spies at LA’s Chateau Marmont. Fresh off her all-weekend party with Paris Hilton, La Lohan was back in vintage form at the celebrity hangout on Monday night. A witness told us, “She was in the bathroom and told her friend, ‘Oh, my God, do you think everyone saw me fall flat on my face? I hate myself.’ Then she stepped on my foot so hard.” The spy said Lohan, in a short, black romper suit and strappy heels with her hair in a bun, “looked wobbly, and on her way back to her table outside stumbled over again. The next time she got up, hotel security had to give her a hand.” Lohan partied in front of more demure stars including Olivia Wilde and Emily Blunt, who remained low-key — at separate tables — and left at about 1 a.m. with her friends. Lohan’s rep fired back, “As usual, a pack of lies from people with nothing better to do with their lives than make up stories about a famous person.”