The men’s steam rooms at Equinox gyms are such a hotbed of lust, one Manhattan outpost let its members hold orgies there, a lawsuit claims.

A man who complained after a masturbating stranger allegedly laid a hand on him during a steam said he heard the orgy claim from a manager in October.

He’s one of five men who banded together in a new class-action lawsuit against Equinox, claiming the gym ignores “the reprehensible conduct occurring in [its] steam rooms.”

Twice in three days, the 34-year-old marketing rep, identified as R.S. in the suit, got more than expected when he went in for a steam at the Columbus Circle location.

“The next thing I know I feel a hand on my thigh and I jump up and I say, ‘What the hell!’ and there’s one guy sitting there masturbating and the guy who touched me was masturbating as well,” he told The Post.

He told a locker room attendant, but R.S. saw the handsy man working out the next day, he said.

When he encountered more masturbating males on his next steam, he escalated his complaint. A manager mentioned the Thursday night orgies, where a clique took over the steam room.

Equinox has “done nothing to correct the problem,” said R.S.’ attorney, Marc Held.

The gym revokes the memberships of those accused of lewd behavior, an Equinox spokeswoman claimed.

R.S. decided to join the Manhattan Supreme Court case after another man spoke to The Post in April about encountering masturbation in Equinox’s steam rooms.

“I am as gay as they come. It’s not about gay or straight, it’s about right and wrong,” R.S. said.