No wonder Heather Mills is continually trying to spank Paul McCartney in the former couple's divorce case. It's all she knows.

We've uncovered yet another lewd photo of Mills from a 1993 photo shoot. The one below, along with other Heather Mills pics from that time, were part of a "sex education manual," according to the one-legged digger of gold.

Well, if that's the case, Kim Kardashian has read it cover to cover.