EXCLUSIVE

Paris Hilton has hit rock bottom ... because now even Octomom is labeling the socialite a "moron" for her recent anti-gay rant.

Yesterday at her home, Octo severely bashed Paris for saying gay men are horny, disgusting people who probably have AIDS -- calling PH every name in the book and some that aren't (watch it ... trust us).

Octo goes on to prove her love for "the gays" by announcing she's performing her new song at a gay strip club -- and then belts it out a capella ... it's pretty terrible.

Purely for comparison ... here's the music video with Octo's voice auto-tuned. It's still terrible.