The episode opens with Barney telling Lily an inappropriate joke about the difference between peanut butter and jam that apparently makes Lily not talk to the group for four weeks. Maternity leave anyone? Very funny way of doing it though.
In the main storyline, Ted has started his own architecture firm, Mosbius Design, out of his house. Yet Ted looks for any excust o procrastinate from actually calling clients and getting work, such as looking for the perfect pen and mentoring his new intern, PJ. Much to Barney's disappointment, PJ is actually a guy and not some hot chick Ted hired to sleep with. In fact, Robin ends up sleeping with PJ. She apparently has become so desperate from working so late she'll settle for anyone in her house. However, when Robin's relationship with PJ gets in Ted's way, he fires PJ, who ends up being too clingy for Robin anyways. Robin dumps him and Ted rehires and they end up sleeping together again! There's no ending this vicious cycle.
Meanwhile, Marshall is worried about being subject to budget cuts and being laid off. Barney convinces him he needs a "thing" to guarantee his job security. The guys who keep their jobs at work all have a thing such as good guy, toy guy, youtube clip guy, etc. Marshall eventually settles on Sports Guy but finds it's too much work and stress.
Barney, meanwhile, is getting jealous over Robin and PJ and has no one to talk to with Lily gone. Just as he's about to tell Marshall, Marshall let's him know Lily already told him. Marshall helps Barney out by hiring PJ to be his paralegal and run the fantasy sports league for him, solving everyone's problems.