Spears made not one but two cameos on "How I Met Your Mother", playing Abby, a receptionist at a tattoo removal clinic who is madly in love with Ted (Josh Radnor), even though he barely knows she's alive.

Abby returned six episodes later, this time determined to prove she's over Ted...by hooking up with Barney (Neil Patrick Harris). A lot. They even get falsely engaged, though it takes poor Abby a while to realize Barney has no intention of marrying her. Or anyone.

https://ew.com/tv/britney-spears-best-tv-performances/