This is the movie that Mattel does not want you to see. Screened in some film festivals, but most of the time screenings are cancelled because Mattel files lawsuits.
In short, Barbie is in an unhappy marriage. Ken plays around with every female he can, and gives his wife minimal attention. So when their maid puts the moves on Barbie, she is more then receptive. We also get to see some other rather kinky sceens.