THE basement auditorium of the Jewish Community Center on the Upper West Side is a sincere space. Big, brown and bare, it suggests a school gym, a place for officially sanctioned fun — which made a recent concert by Schmekel, a raucous klezmer-core punk band made up of “100% trans Jews,” all the more surprising.

“Schmekel” means little penis in Yiddish, and is a play on the fact that all four members were born female but now identify themselves on the masculine side of the gender spectrum. It’s an appropriate name for a band that started as a laugh.

“I made a joke at a diner about how it’d be funny if there were an all-transmasculine band called Schmekel that was all Jews,” said Lucian Kahn, 29, a guitarist and vocalist.

On the spot, Nogga Schwartz, a bassist, and Ricky Riot, keyboardist and vocalist, both 26, joined up. Within a few weeks they had found a drummer, Simcha Halpert-Hanson, also 26.