Lindsay Lohan ain’t the only one saying one thing and doing another when it comes to her long history with substance abuse.

While Mischa Barton adamantly claims she’s sober and clean, eyewitnesses at a recent Fashion Week event tell Page Six that they beg to diiffer.

After stumbling in line at the G-star after-party at the Bowery Hotel, “she kept saying, in a really spacey, weird British accent, ‘Like, I’m with the deejay. I to tally know the deejay. I’m here for the deejay. She was slurring her words.”

Wait — it gets worse. Once inside, Miss Barton “needed to be escorted to the deejay booth” where she stood “for about an hour, dancing in her own world. I don’t think her eyes were open to full capacity — or even half capacity — the whole time she was there.”

Four words: Lindsay….Mischa….reality show.