Credit: 2010 RAMEY PHOTO

Another style blunder for Britney.

The singer, 28, stepped out in jeans, a cardigan and sneakers to go shopping at the Only Hearts boutique on Santa Monica's hip Montana Avenue Wednesday.

Before leaving the shop, Spears oddly slipped into a lace-trimmed nightie and blue leather boots.

Judging by photos that hit the web Thursday, she also forgot to put on a bra.

Spears didn't seem to mind.

Accompanied by bodyguards, the mother of two kept smiling as photographers snapped away.