'Wolf of Wall St' Stripper -- My Lap Dance Didn't Arouse DiCaprio -- Maybe He Taped It Down

It takes a lot to get Leonardo DiCaprio turned on ... so says the actress who had the enviable task of giving Leo a lap dance in "The Wolf of Wall Street" ... but failed to get a rise out of him.

Tracie Jayne -- who was cast as a stripper in the movie -- says she threw herself into her work ... grabbing DiCaprio by the hair ... licking his neck ... and biting his ear -- but wasn't able to arouse little Leo.

"Maybe he was wearing Spanx or he taped it down or ... thought about his dead grandmother," she joked.

Jayne -- who's actually a standup comic by profession -- insists Leo still had a good time ... telling her to "go for it."

You gotta hear her tell it.