The clothes worn by Britney Spears' in U.S. TV sitcom HOW I MET YOUR MOTHER are to be auctioned. Spears will make a cameo appearance in the show, playing a secretary opposite Neil Patrick Harris. And the wardrobe from the show will be sold at an online auction to benefit the Natural Resources Defense Council, an environmental organisation. The week-long auction begins on Monday (24Mar08) - one day after the episode featuring the pop star is set to air on Sunday (23Mar08). At least six items, including a navy print Juicy Couture dress, a yellow Nannette Lepore dress and a cream Nannette Lepore cardigan, will be sold.