Lindsay and Ali Lohan"s Chain-Smoking Sisters" Night Out

Lindsay Lohan was all dolled up on Tuesday night when she arrived to her usual table at Chateau Marmont in West Hollywood.

With sister Ali in tow, Lindsay sported a black dress, sky-high heels and a sparkly coat at her regular haunt when the gals arrived at around 11 p.m..

“Lindsay chain-smoked and typed on her phone,” an onlooker tells us. “She [later] moved tables to join a couple who were having wine. She began chatting with them and became more involved in the conversation.”

Meanwhile, Lindsay wasn”t the only Lohan puffing away.

“Ali was bouncing around tables and going to the bathroom and smoking outside by the valet,” the source says. “She looked very thin and seemed to be acting much older than her actual age.”