They were having fun, fun, fun until someone took their surfboard away.

And the Grey Eagle Resort and Casino wants that surfboard -- signed by two memb ers of the Beach Boys -- back.

It was stolen by a pair of cheeky and ungrateful thieves following the group's concert there Aug. 28.

It was a promising night that quickly hit a sour note, said casino Entertainment Director Russ Giroux.

"It was a fantastic night and the Beach Boys invited a couple back to hang with them backstage and they were left unattended," he said.

"The guy very audaciously absconded with the surf-board.

"We sure would like the surfboard back."

The weathered blue and white surfboard was lent by a friend as a prop for the show, and signed by two of the Beach Boys, including group co-founder Mike Love.

A surveillance photo shows a woman in her 20s, apparently ecstatic at the sight of the stolen board, as a man wearing a baseball cap carries it out the door before they leave in a taxi.

"Our security people assumed it was his memorabilia," said Giroux, adding the couple's surfboard crime unleashed a wave of disgust.

"It's quite ignorant -- they were invited back as guests, it's like stealing something from your house."

He said the Beach Boys profusely apologized for the theft. "We're in no way blaming the Beach Boys -- they were as much victims as we were -- but we will be changing some policies now," he said.

The Tsuut'ina Police are investigating the matter but the casino says no charges will be laid if the item is returned.

Anyone with information on the theft are asked to call the Grey Eagle Event Centre box office at 403-385-3747 or the Tsuut'ina Police at 403-271-3777.