Long before ex-con Martha Stewart shed her electronic anklet, one of the most controversial of her “Apprentice” contestants was doing a little stripping of her own.

Bethenny Frankel – who dated the son of one the reality show’s judges – starred in the 1994 flick “Hollywood Hills 90028” as a bisexual serial killer at Hollywood High who romps topless at the drop of a hat.

One scene finds the bodacious beauty, then 23, rubbing suntan oil on a female classmate before engaging in a steamy lip-lock.

Another scene leaves little to the imagination as she makes love to a nerdy male classmate on a mirrored waterbed.

Although the R-rated feature is billed as a thriller, it bears all the hallmarks of soft-core porn, complete with atrocious lighting and sound.

At one point, a hunky classmate congratulates Frankel on her ability to simulate a certain sex act using a banana; she replies: “Tune in tomorrow when I do intercourse using a carrot and a doughnut.”

Frankel’s only other big-screen appearance was a bit part in “Wish Me Luck.”

The 1995 teen flick tells the story of “a genie sent to a junior college to turn a nerd into a man.”