Britney Spears as Abby
Britney Spears wasn’t still a huge name by the time she appeared on How I Met Your Mother, but let’s be real, she’s still Britney Spears. Like Katy Perry’s Honey, Spears’ Abby is completely naive and a bit trashy (what are you trying to say about pop music Bays and Thomas?).
Not only is Abby great in her first appearances as Stella’s receptionist, but she comes back later in season three for a totally unexpected appearance as the one who’s trying to ruin any chance Barney has at sleeping with another girl. She’s not able to hold out for long, and the result is a hilarious scene where she believes that Barney’s fake proposal is a real one. I’m not the only one who thinks that Abby was legendary either, as in 2009 Spears was nominated for a well-deserved People’s Choice Award as Favorite Scene Stealing Guest Star.
Billy Zabka as Himself
One of Barney’s more amusing character traits is the fact that he always roots for the bad guy in movies. He loved Hans Gruber, pulled for the guy running detention in The Breakfast Club, and even cried when the Terminator’s little red eye went out at the end. But the one villain he loved more than any other was the Karate Kid himself, Johnny Lawrence. So when Billy Zabka appeared at Barney’s bachelor party, Barney couldn’t have been any happier.
Zabka’s appearance went over so well with fans that they decided to bring him back for all of season 9. He’s one of Barney’s guests at the wedding and at one point he’s even the best man. It turns out that he’s not only a sensitive guy who hates to be hated, but he’s also a poet beloved by Gary Blauman. Billy Zabka is a multia-layered character, and an excellent addition to How I Met Your Mother.