Haha/Oh dear. Ali Lohan, sister of Lindsay, was on Letterman last night, presumably to promote her and mama Dina's ominous new reality show. And, poor thing, as Dave was signing off, he accidentally called her Lindsay. I mean, how could he possibly get them mixed up? Lindsay is a once-popular tween idol with substantial drug and alcohol problems. Ali is a soon to be once-popular tween idol with substantial drug and alcohol problems. Geez. It's like comparing apples and the seeds that later become apples. Clip above.