She first appeared in Season 3, Episode 10, titled How I Met Everyone Else. This episode is particularly fondly remembered by fans for it's humor and the unique dynamics it introduced among the main characters.
Blah Blah meets Ted Mosby (Josh Radnor) while playing World of Warcraft, but she insists that he tell his friends they met in a cooking class. This playful deception sets the tone for their relationship, which quickly reveals itself to be more complicated than it initially seems. When Ted brings her to MacLaren's, he recounts the story of how he met everyone else, leading to a series of humorous and revealing moments.
As the night unfolds, Blah Blah's character becomes increasingly unpredictable, showcasing her position on the "hot-crazy scale." Her jealousy flares when Ted shares stories about his past relationships, particularly his connection with Robin, prompting her to try to outdo Robin in various ways throughout the evening. This rivalry adds a layer of comedic tension to the episode, highlighting the show's signature blend of humor and heart.

In a later episode titled Rabbit or Duck, Lily Aldrin (Alyson Hannigan) mentions Blah Blah, revealing that she has been committed to Bellevue Hospital Center, hinting at the more eccentric aspects of her personality. This detail adds depth to her character, suggesting that her quirky behavior may stem from deeper issues.
The character of Blah Blah, while only appearing in a single episode, left a lasting impression on fans. In the series finale, Older Ted reflects on his past relationships and, in a moment of realization, remembers that Blah Blah's real name is Carol. This nod serves as a reminder of the impact she had on Ted's journey, despite her brief appearance.
Abigail Spencer's portrayal of Blah Blah is a testament to her talent as an actress, capable of bringing a unique and memorable character to life. Her performance in How I Met Your Mother remains a cherished part of the show's legacy, showcasing the humor and complexity that made the series a beloved classic.
Interessting facts:
- Blah Blah makes custom handbags which have been sold in Japan.
- Blah Blah is the first character whose name Future Ted can not remember, the second being Honey.
- Blah Blah says to "call me Blah", which may mean her full first name is Caroline (or something similar).
- Blah Blah made Robin's list of Ted's five worst relationships coming in at number 5.
- According to Lily, Blah Blah is committed to Bellevue Hospital Center, a psychiatric care facility at the time of Rabbit or Duck.