A Dirty Shame (2004)

Sylvia Stickles runs a convenience store with her husband and mother-in-law. One day, Sylvia is hit on the head and transforms from an uptight prude to a sex-crazed lunatic. As she goes on a rampage through town, Sylvia attracts the attention of Ray Ray, a sexual healer and tow truck driver in search of the world's greatest orgasm. Their sexual revolution, however, causes a class war in their tiny Baltimore community.

Source: TMDb