That sounds like a good question and can draw the attention of many who’d be trying to figure out what’s the difference between peanut butter and jam. And, of course, they’d be right in their thinking, and all the answers from this perspective would be right. But wait! Your innocent answer about the difference between peanut butter and jam isn’t what’s needed here. This is a joke. A dirty one at that.
The joke comes from an American sitcom titled How I Met Your Mother, or simply HIYM. The sitcom is a creation of Carter Bays and Craig Thomas and ran between 2005 and 2014. It follows Ted Mosby, the series’ main character, together with his friends. In the series, it’s the year 2030, and Tedd is recounting to his daughter and son the events leading to his meeting their mother. HIMYM was jointly produced by 20th Century Fox and Bays & Thomas and was syndicated by the 20th Television.
The series was inspired by Bays’ and Thomas’ friendship while both were living in New York. It consists of 208 episodes with only four directors. The sitcom has unique humor and structure and incorporated dramatic elements. It enjoyed wide popularity throughout its run.
So, what then is the context of the joke? Well, it’s in a scene where all the three main characters, that is Barney, Ted and Marshall chilling and enjoying one another’s company. While at it, they’re telling a dirty joke, and Lily happens to walk by there. Lily wants them to share the joke. All the others refuse to share the joke, but Barney agrees to it. So he whispers it to her. Lily finds the joke so dirty that she walks off and four weeks pass without her ever talking to them.
And what’s the joke in all this? You may ask. Well, Barney asks Lily to tell her the difference between peanut butter and jam. She ponders for a while trying to figure out what the difference could be. After realizing she probably wouldn’t find the difference, she gives up and tells Barney that she doesn’t know. She then asks him to tell her the difference. And the answer Barney gives her is what makes the joke very dirty. He tells her he can’t butter his dick up her ass, but can certainly jam it up there. This is what prompts Lily to walk off and not talk to them for four weeks.