How I Met Your Mother May Not Have Survived Without Britney Spears

If you're a fan of the long-running series "How I Met Your Mother," you know that pop star Britney Spears memorably pops up in the third season of the beloved CBS sitcom ... so how did that happen, and how did Spears' guest role basically save the show?

During a Reddit AMA (ask me anything) in 2013, Carter Bays, who created "How I Met Your Mother" alongside Craig Thomas, was asked if any of the show's guest stars had ever specifically asked to join the series. Apparently, Spears did just that. "We got a call a few weeks after the writers' strike [in 2007] ended saying that Britney Spears wanted to be on our show," Bays responded. "And she specifically wanted to be in the episode 'Ten Sessions,' which sent a chill down our spines, because that's the one where we meet Stella [Zinman, a love interest for Josh Radnor's Ted Mosby]."

As Bays put it, he was a little worried about what Spears' request might mean. "I immediately imagined Britney playing Stella and had a minor panic attack, because it's such a big role and needed a proven, experienced actress like Sarah Chalke [the 'Scrubs' alum who ultimately played Stella]. But to her credit, Britney liked the character of Abby and wanted to play that part. So we said sure! And by golly, she put our show on the map. It can't be overstated. Britney Spears rescued us from ever being on the bubble again. Thanks, Britney!"

So who exactly is Abby on "How I Met Your Mother?" She's Stella's naïve, sweet receptionist who takes an immediate liking to Ted Mosby, though he develops a pretty big crush on Stella, the dermatologist removing his lower-back tattoo, as soon as she begins his laser treatment. Every time Ted interacts with Abby, she's desperate for his attention and apparently has little to no idea that it's Stella he's sweet on, so she keeps trying, even changing her appearance and reading books designed to impress Ted every time he visits Stella's office.

This escalates into an unsettling arrangement where Abby and Barney Stinson — one of Ted's best friends and a notorious womanizer played by Neil Patrick Harris — end up joining forces, even though Barney is just using Abby for sex and Abby is (misguidedly) trying to make Ted jealous. After the two have a one-night stand and Barney never calls Abby again — which is sort of his whole deal — they reunite in the season 3 episode "Everything Must Go" and pretend that they're together at the show's main hangout MacLaren's Pub (they're wearing matching sweaters, and when Barney announces that they're engaged, Abby forgets all about the bit and thinks that he's serious about marrying her). Abby is, frankly, a pretty irritating character, but it's funny that she's played by Britney Spears ... and Carter Bays' instincts were dead on that he needed a more experienced actor to play Stella.

Britney Spears is far from the only major celebrity to guest star on "How I Met Your Mother" throughout its run. Some, like Robin Thicke, Regis Philbin, and Kim Kardashian, appeared as themselves, but a few other pop stars got in on the fun too. In season 6, Katy Perry shows up as Honey, an unbelievably gullible character who will believe basically anything anyone tells her (in his voiceover, the Bob Saget version of Ted Mosby says he can't recall Honey's "real" name, so he calls her that because whenever she speaks, you just want to say "Oh, honey"). Enrique Iglesias briefly plays a boyfriend of Robin Scherbatsky's (Cobie Smulders) whom she dates early in season 3, and Jennifer Lopez appears in the season 5 episode "Of Course" as dating guru Anita, who discovers her biggest hurdle in Barney. Nichole Scherzinger, the former Pussycat Doll turned Broadway star, pops up in season 6 as Glitter, a former co-star of Robin's from back when she was known as "Robin Sparkles," a Canadian pop star, and even Carrie Underwood appeared in season 5 as Tiffany, a girl who has Ted on her proverbial "hook."

Martin Short, John Lithgow, Katie Holmes, James van der Beek, Laura Prepon, and Bryan Cranston are just a few of the other famous people who showed up on "How I Met Your Mother" — Joe Manganiello also had a recurring role on the sitcom early in his career — but it's fascinating to know that not only did Spears request her role, but she basically saved the show. You can watch her episodes of "How I Met Your Mother" on Hulu now.