Flash mob? This was a mob flash.

About 150 near-naked runners took part in yesterday’s Cupid Undie Run to raise money for the Children’s Tumor Fund.

“Nothing draws a big crowd like people running in their underwear,” said Chad Leathers, 27.

He ought to know, since all he wore were sneakers, a scarf and boxer shorts festooned with red hearts as he set out on the one-mile Hudson River Park jog by the West Side Highway.

“At the end of the day, it’s for the kids,” added Jared Dimbort, 26. “But it’s always fun to take off your pants and run around in the freezing cold. It’s such a New York thing to do. I’ve been training for this day my whole life!”