A woman got a rude surprise when she politely slid to the other side of a bench to make room for a fellow Westbury concertgoer — a backside full of splinters.

Linda Vanston, a schoolteacher from New Jersey, is suing the NYCB Theater at Westbury on Long Island over the injury.

“She was not aware that the bench had exposed sharp shards of wood sticking out of it,” said her lawyer, Rosemarie Arnold.

“She stood up to look at what had happened, and she saw the frayed wood on the bench.”

Vanston, 55, was wearing silk pants and sitting on the bench outside the Engelbert Humperdinck concert on April 29, 2011.

The 1,000 splinters that wedged in her thighs and buttocks have been coming out, around a dozen a day, since then, Arnold said.

Vanston has received “painful injections to help dislodge,” them, her Nassau County Supreme Court suit says. She also had to take time off work and has limited mobility from the incident.

Vanston and her husband are seeking unspecified damages.

Reps Live Nation, which owns the venue, did not return messages for comment.