Well the media magnet couldn't have been more serious.
In an interview with E! Online's Kristin Dos Santos, actor Neil Patrick Harris set the record straight saying that Spears approached the show and asked to guest star and not the other way around.
"Working at 'How I Met Your Mother' has been so terrific," Spears said said in a statement sent to The ShowBuzz. "Everyone, including the cast, the crew and the producers, has been wonderful and Abby is such a fun girl to play. I'm having a blast!"
Spears has previous TV sitcom experience playing a character on a 2006 episode of "Will and Grace." She was also the host and musical guest on "Saturday Night Live" in 2000.
CBS spokesman Kelli Raftery said Spears attended a table reading with the cast on Monday, did a "run-through" on Tuesday and filmed scenes Wednesday. She was scheduled to shoot scenes Thursday and Friday.
While the pop diva is filming on set, "How I Met Your Mother" had to up the ante on security.
According to Harris, while Spears is on set on Stage 22 at the Fox lot on Pico Boulevard in Los Angeles, the crew has to wear wristbands to "keep meddling blogger friends from just strolling on to set to snap camera phone pics," Harris said. "It's like the ultimate afterparty!"
One day Harris really felt the impact of Spears' fame when he didn't have his wristband; he couldn't get on his own set. Although it took a little coaxing, Harris "had words" with the guard who finally let him through.
"Britney has shown up three days out of three so she's batting 1,000," Harris said.
When asked if Harris' character - the narcissistic womanizer - Barney would have a shot at Britney, he said "Barney would out-Adnan Adnan."
Harris also said that he's sorry actress Alicia Silverstone couldn't do her role in the same episode as Britney, but NBC's "Scrubs" star Sarah Chalke is a "perfect fit for the show" and matches Radnor "beat for beat" in every scene.
"We couldn't be happier to have Sarah Chalke joining us to play a new love interest for Ted, Dr. Stella Zinman. Not only is Sarah smart, funny and charming, but we already know she looks damn good in a labcoat," Craig Thomas, the show's executive producer and co-creator said.
"It's an interesting change of pace for her (Spears) to be around a group of people that don't have an agenda with her or want to take her picture. So I don't know how often she's just hung out with other actors and 'normal' regular people," Harris said. "I hope she enjoys the experience."
"How I Met Your Mother," returning Monday with all-new episodes following the writers strike, co-stars Radnor, Jason Segal, Alyson Hannigan, Cobie Smulders and Neil Patrick Harris as twentysomethings living in New York City.
Spears has been under the conservatorship of her father, James, following bizarre behavior and two hospitalizations. She is also locked in a custody battle with ex-husband Kevin Federline over the former couple's sons, Jayden James, 1, and Sean Preston, 2.
By Melissa Castellanos