"Desperation Day" is the sixteenth episode of the sixth season of the CBS sitcom How I Met Your Mother and the 128th episode overall. It aired on February 14, 2011.
When Lily mentions how lonely she is with Marshall still living with his mother in Minnesota, Barney explains the story of Desperation Day, the day before Valentine's Day. Barney claims that single women will find themselves desperate and easy to hook up with on the eve of Valentine's Day. Robin decides to prove him wrong and says she will be hanging out with her female colleagues that night, though Barney believes they will be just as desperate as any other woman. That night, Robin hangs out with her colleagues, while Barney hits on women. However, Barney then takes interest in one of Robin's colleagues, Nora, who had just arrived. Nora privately tells Barney that unlike Robin and her other colleagues, she actually loves Valentine's Day. Barney hints that the fact she tries to appear romantic comes across as desperate, and instead begins explaining how to play laser tag. The two return to Robin to find her friends have left, as they had gone home with two other guys. Nora soon leaves as well, to Barney's disappointment, but gloats to Robin how her colleagues had fallen for Desperation Day. Robin however points out its after midnight, and Barney had failed to hook up with a woman on Desperation Day. She also claims Barney is beginning to like Nora; though he denies it, Robin later invites Nora to play laser tag with Barney. Future Ted states it was the first time Barney had been on a date on Valentine's Day.
After confessing their feelings for each other in the past episode, Ted and Zoey are happily dating though they agree to take things slow. Zoey invites Ted to help bake cookies one night; when Ted describes this is as odd to the rest of the gang, they tell him "baking cookies" is essentially code for staying over for the night. Ted arrives at Zoey's apartment with an overnight bag, but she sends him home, saying he was being presumptuous. Later Zoey apologizes and tells Ted she is ready to get serious. However, Ted feels there is added pressure, as Zoey has just separated from her husband, and begins feeling anxious.
Meanwhile, Lily misses Marshall, and is especially disappointed as it is Valentine's Day; the couple has an odd tradition of watching Predator every year on February 14th. After admitting to have used a stuffed pillow as a stand-in to Marshall, Lily finally heads to Marshall's home to convince him to return. Marshall doesn't wish to leave so soon, but it becomes clear Marshall's mother has become annoyed with his presence, though not admitting it to Marshall. Marshall has essentially reverted to his teenage self, playing his old video games and not even realizing how much Lily misses him or his mother's annoyance of him. Ted soon joins Marshall, claiming to help Marshall deal with his loss though in reality trying to avoid the pressure of committing to a relationship with Zoey. Lily finally announces that she is heading back home to New York, leaving Marshall saddened. Marshall reveals to Ted the real reason he has stayed in Minnesota is because he feels lost without his dad, and doesn't wish to return to his life. The two agree to drive back home that night, as flights have been cancelled due to a storm. During the drive, Marshall has trouble seeing the road ahead when the image of his late father appears in his back seat, giving him advice on how he drove in such conditions. Encouraged by his father's words, Marshall makes it back to New York. Lily is later thrilled when Marshall comes home, and the two watch Predator together.
Zoey later greets Ted at his apartment and shows him her own overnight bag. Ted jokingly calls her presumptuous, and the two kiss, thus ending their anxieties about commitment. In the end, Lily is shown having a quiet break-up with her pillow (which she had nicknamed "Marshpillow").
- It was hinted that Ted might develop feelings for Zoey in the episode "The Mermaid Theory." They kissed in the previous episode, "Oh Honey."
- In "Bad News", Barney holds a poster for the 47th Semi Annual Laser Tag Tournament, in which he participates in this episode.
- Ted corrects Robin and Zoey that his British Morning Socks are not slippers. Ted has a habit of correcting people, as shown in "Spoiler Alert".
- The shirt Marshall is wearing while back in Minnesota says "Tarkenton High School Phys Ed.", a reference to Fran Tarkenton, who was previously mentioned in Little Minnesota.
- Marshpillow will return in "Challenge Accepted," as Lily copes with illness while Marshall is away from the apartment.
Barney posts eight Desperation Day cards for ladies to present to men.
- Aside from being Marshall and Lily's annual Valentine's Day tradition, the episode pays homage to the Arnold Schwarzenegger movie Predator when Barney mimics the Predator's clicking sound and thermal vision while on the prowl.
- Marshall is playing Dr. Mario and Ted discovers he has a copy of Super Mario Kart.
- Barney claims to be Huey Lewis and says that Robin's heard the news.
- Barney tells another fake history lesson by saying that Saint Valentine had a "best bro" - Saint Desperatius. While Ted notes that Barney's version of St. Valentine's history is true, it is not completely accurate. Only Christian marriage was outlawed, not all marriage. In that same fake history lesson Saint Valentine and Saint Desperatius give each other a "High V" (high five), and Valentine comments that Robin's counterpart is a "perfect X", referencing the Roman numeral system where 'V' represents 5 and 'X' 10.
- Robin calls Barney a "high-functioning sociopath", which is Sherlock Holmes' self-description in BBC's Sherlock series starring Benedict Cumberbatch.
- Robin points out the "two white Urkels" at MacLaren's, referencing the iconic television character Steve Urkel from the show Family Matters.
- Gray's Papaya is a popular hot-dog restaurant (2 locations) in the West Side of Manhattan. The gang visited one such branch in the season 1 episode "The Limo".
Robert Canning of IGN gave the episode a rating of 7 out of 10.
Donna Bowman of The A. V. Club gave the episode a grade of A-.