Britney Spears Has Colorful Underwear

Britney Spears shows off her colorful underwear while carrying her pet pooch London in Los Angeles, Calif. Tuesday night.

The pop princess was seen shopping at Lisa Kline, entering wearing one outfit and leaving in another.

“[Britney] bought her mom and her sister Christmas gifts, matching gifts,” the store’s rep, Kate Diamond, told People, adding that the pop star also snapped up two By Francine dresses and a Treesje purse for herself.

Upon leaving the Robertson Blvd. boutique, Brit was overheard telling paparazzi and fans, “My sister’s not pregnant!”

Brit‘s 16-year-old sister, Jamie Lynn Spears announced her pregnancy last night after keeping the surprising baby news secret for many weeks.

Jamie Lynn and longtime boyfriend Casey Aldridge expect their first child together June 2008.