Sean Stewart's Playmate GF Daisy Lea: Welcome to Beaverly Hills!

Sean Stewart's gf Daisy Lea is suffering severe memory loss ... is all we can assume since she went shopping in Bev Hills -- without a single stitch of underwear.

Maybe Daisy -- an extremely flexible Playboy Playmate -- was on her way to a photo shoot, but when she and Sean strolled out of Barneys her tiny wardrobe malfunctioned. Or maybe it functioned exactly as planned.

For the record ... Barneys sells underwear.