Mel Gibson Cheated On Oksana Grigorieva With A Porn Producer

Geez Mel, way to pull a Tiger Woods!

Porn producer Violet Kowal has spilled the beans to the National Enquirer, revealing that she had an affair with Mel Gibson ... while his girlfriend Oksana Grigorieva was pregnant!

Kowal claims to have slept with the actor eight times in 2009 during a three month period, and the alleged trysts happened at his Malibu home and his Santa Monica office. "Mel's breakup with Oksana doesn't surprise me at all," Kowal told the tabloid. "Clearly, Mel can't commit to just one woman." Kowal added, "Mel's great in bed! It was the best sex I've ever had!"

Though Gibson's attorney calls the story "an absurd fabrication," this would certainly explain his sudden split from the Russian beauty...