The history of stunt-casting on "How I Met Your Mother" is a mixed one – with Britney Spears delivering a bad performance in one of the series' best episodes (and a better performance in a later episode), Enrique Iglesias' pretty memorable turn (as opposed to Mandy Moore's), and Carrie Underwood upstaged by a teacup pig … Continue reading 'HIMYM's' Barney meets his match: J. Lo