A night on the town went haywire for some “Real Housewives” when Ramona Singer defended a drunken creep at a fancy party — and was then ejected with the guy.

Singer began the evening at Sushi Roxx with cast mates LuAnn de Lesseps and Sonja Morgan before hitting a party hosted by Dorinda Medley’s boyfriend John Mahdessian at his haute dry cleaner, Madame Paulette.

That’s when an overserved guest — described by a source as “an uninvited drunk who once dated LuAnn” — started “harassing” Morgan and Singer.

Mahdessian jumped to the ladies’ defense at the packed party, but “Singer oddly asked the drunk to stay, with an ensuing screaming match,” sources said.

That’s when the dry cleaning magnate “had them both removed” in front of guests including Consuelo Vanderbilt Costin and Daniel Joory.

“People applauded, and Mahdessian declared, ‘I took out the grime!’” But Singer was then seen on the street, laughing.

The party also celebrated designer Malan Breton. On Thursday, Mahdessian’s hosting the Oui R United bash at Beautique with P.E. Guerin and Better World Awards producer Gina deFranco.

This article originally appeared in the New York Post's Page Six.