What the fuck. It's not a pun, stop trying to read all kinds of lol so clever shit into this.
Back in the first season, there was an episode where they were eating in a restaurant, I'm pretty sure it was the Yaz and Kaz gym episode, and Pikachu tried ketchup and really liked it. It cried when the ketchup bottle broke.
It was adorable, and Pikachu's love for ketchup has been referenced ever since.
