Following in the brave footsteps of Britney Spears, Carrie Underwood will make a tightly scripted guest appearance on the CBS series How I Met Your Mother, playing a blonde love interest for Ted (Josh Radnor). Instead of Britney's stalker-like receptionist cameo, Underwood will mark her acting debut as an "enigmatic pharmaceutical sales rep" in March. Merry prescription-pushing! [People]