Brit Behavin' in Sitcom Cameo

Britney Spears is acting like a lady on the set of the CBS sitcom How I Met Your Mother, her cast-mates report—and Spears is "having a blast" herself, she tells People. Spears arrived promptly for work at a Los Angeles studio early yesterday morning, then again this afternoon after keeping a scheduled visit with her two young sons, the mag adds.

Spears "knew her lines better than I knew mine," joked co-star Josh Radnor of the pop princess' role as a dermatologist's receptionist. The episode is scheduled to air March 24. Brit even dropped the idea of extending the role, People reports. A trace of the old Brit did linger, however: "She chewed gum obsessively," a source said. (More CBS stories.)