Britney Spears takes a break from her hectic schedule of misbehaving to do something radical this week: work! She's been busy guest-starring on the hit CBS show, How I Met Your Mother. Stepping into the shoes of a receptionist at a dermatologist's office named "Abby," has been "terrific," reports Brit. "Everyone, including the cast, the crew and the producers, has been wonderful, and Abby is such a fun girl to play. I'm having a blast!" Brit's bit part took the cast by surprise. "We were literally just filming last week and told, 'You're not going to believe who just called and said they wanted to be on the show,'" recalled Emmy-winning lead Neil Patrick Harris. Even more surprising - she's no trainwreck! Co-star Alyson Hannigan admits she's "quite impressed" with Britney's acting.