Snooki -- I'm NOT Pregnant ... And Stop Calling Me Fat!

Snooki is calling radishes on a report that she's pregnant -- claiming not only is she NOT pregnant, she's insulted by the insinuation she's fat.

The "Jersey Shore" star left Sirius XM studios in New York moments ago -- where she appeared on the Opie & Anthony radio show -- and a photog flat-out asked if the pregnancy rumor was true ... Snooki firmly replied, "NO!"

Worse, Snooki's livid at rumors she's gained weight, claiming, "Why are people calling me fat? That's so rude!" Snooki said she does wanna get pregnant one day though ... when she gets married.

As for the Opie & Anthony interview (below) -- Snooki said the media outlet that reported the story is just like one of the bullies who terrorized her in high school ... and she has a message for the offender ... "I hate you."

Check out the vid for Snooki's Super Bowl favorite. You won't believe it.