Barney is told by one of his sexual conquests that she may be pregnant with his baby. When Barney learns that she isn't pregnant, he celebrates by creating what he hopes will be a new national holiday: Not a Father's Day. Ted and Robin try to open Barney's eyes to who are not fathers. Meanwhile, Marshall and Lily are contemplating having a baby. When Marshall has to skip a planned baby making session due to a work meeting, Lily begins to wonder if she and Marshall really are ready to be parents. She calls in Robin and Ted for their advice, they who are on opposing sides of the issue. As Robin and Ted debate the general issues of parenthood, Lily, with the assistance of a bottle of wine, goes to Marshall's office invading his meeting to tell him her decision in only the way a drunken wannabe mom can.
While Barney celebrates a pregnancy false alarm, Marshall and Lily try to figure out if it's time to have a baby.
- Barney started the night with a quick tutorial on "The Cheerleader Effect," the phenomenon of a group of women who appear to be hot, but only as a group. Each individual in the set, it turns out, is incredibly unattractive. He said it's also known as "the Bridesmaid Paradox, Sorority Girl Syndrome, and, for a brief period in the mid-90s, the Spice Girl Conspiracy -- Scary Spice, indeed."
Barney then took a call and discovered he's apparently going to be a dad. There was still some question as to whether his fling was really pregnant, and Lily suggested it might be a false alarm. "If one of my little Michael Phelpses got loose, he's swimming for the gold." He started to panic, wondering :who in their right mind would want to have kids."
Marshall and Lily were coming down with baby fever after seeing babies all over the place. They started to get down to business when Robin, unemployed and living with them, emerged and sat with them on the couch. They asked Ted if the crabby Robin would stay with him for a night.
Barney had a heart to heart with God, asking him to get him out of his predicament. Just then, his cell phone rang, in church, and he took the call. Barney danced with joy at the news that he wasn't a father. He wanted to create a holiday, "Not a Father's Day." Marshall got news that he couldn't have his special night with Lily because he had a "breakfast" meeting with clients from China, which meant he had to work the night. Lily spilled the baby idea to Ted and Robin, then asked whether they thought she and Marshall were ready to have a baby.
Lily worried that Marshall was only seeing what was cute about having a baby and not the practical stuff. She was afraid all of the work would fall on her. Lily had Ted, pro-baby, and Robin, anti-baby, present their cases. Then they teased Ted because he's basically already a dad. He tells corny jokes, lectures everyone and makes silly comments to waitresses at restaurants.
Barney, meanwhile, was starting to hawk merchandise for "Not a Father's Day," which included a "World's Greatest Not a Dad" mug, and "Who's NOT Your Daddy?" T-shirt, "both available at NotaFathersDay.com," he said. (Yes, the site's real. Look it up). Barney's prototype greeting card included an image of what appeared to be an Asian hooker. "Because on Not a Father's Day, you get a Thai you'd actually wear," Barney explained, before asking Marshall for a "wordplay five."
Ted said Robin was against babies because she's scared of them. Robin made a reasoned argument about Lily having to make sure she's secure in who she is before becoming a mom. But Lily found their neighbor's baby's sock under the couch and caught the baby bug. Before they knew it, Lily was gone and had drank an entire bottle of wine. Next we saw, she was laying on Marshall's desk at his office, saying, "Put a baby in me, Marshall. I'm ready."
Ted and Robin went back and forth about their positions on babies, with Robin teasing Ted for being girlie and Ted telling Robin she doesn't have a heart. Back at the bar, Barney was swearing in "Not Dads," who took an oath on a box of condoms.
Back at Marshall's office, a drunken Lily was distracting Marshall with her baby-like antics and her disrobing while he was trying to give his presentation. He drove her home and she fell asleep in the car.
Ted discovered that Robin had stolen the baby sock and kept it in her purse. She was warming to the idea, but said she wasn't in a position to have a kid because she had no job. They agreed she could move in with Ted until she got back on her feet. Meanwhile, Barney was basking in the glow of the great group of bros he'd assembled in his "Not Dads" club. But Ted and Robin told him to look closer at those guys and notice that he had a "Cheerleader Effect" of his own in the works. All of the guys were complete losers. Barney then found the baby sock and marveled in its cuteness.
The next morning, Lily apologized for her drunkenness the night before and assured Marshall she knew he'd be a great dad based on how he took care of her. Marshall, then, said he didn't want to be a dad right away because he works too much and was so new at his job. He said he wants to have kids someday, but wants to be ready for it.
A drunken Barney ended the night singing "Cats in the Cradle" at a karaoke bar while clutching the baby sock.