Ashton Kutcher or Jessica Simpson?
Here's the perfect Halloween costume idea for Ashton Kutcher... a little make up and a blond wig and you're Jessica Simpson! (actually he's such a dead wringer, all he need's is the wig.)

Thanks to Mugato on Fark for the comparison ("Jessica Simpson looks like Ashton Kutcher in drag")

Jessica Simpson plays dirty boob ball
Ashton Kutcher's gnarly neck beard
The "Which Simpson would you pick?" game
Ashton Kutcher's Punk'd failures