Did Bristol Palin cross the line...with her border line GAY SLUR?

Bristol Palin's heckler -- the one who screamed, "Your mother's a whore!" at a West Hollywood bar last night, and he's not ashamed at all.

Stephen Hanks is a 47-year old L.A. consultant who would not say what he consults on. He did, however, tell us this was not a setup.

As for Hanks' thoughts on Bristol's comment -- jumping to what turns out to be the correct conclusion that he's gay -- he has more choice words for Sarah's little girl

Bristol Palin stood face to face with a very ANGRY Sarah Palin hater at the Saddle Ranch on the Sunset Strip last night ... after he screamed at her, "Your mother's a whore."

It all went down after Bristol rode the mechanical bull -- when the man shouted, "Did you ride Levi like that?"

During the confrontation, the man called Sarah "evil" -- and Bristol replied, "Is it because you're a homosexual and that's why you hate her?"

The man responded, "Pretty much ... and why'd you say I'm a homosexual?"

Bristol shot back -- "Because I can tell you are."