Ah, Barney Stinson, how men all around the world love you for your witty, machismo one-liners. In a season 4 episode of How I Met Your Mother, Mr. Awesome — against the wishes of Ted and Marshall — poses a question to Lily: “what’s the difference between peanut butter and jam?”
Considering that all we saw was Barney mouth move as he delivered the punchline, the answer was never revealed. However, he probably said:
“You can’t peanut butter your dick up someone’s ass.”
Needless to say, Lily was not amused and vowed to never hangout with Barney again.
Now, that may or may not be the actual punchline, so feel free to create your own. Let us know what you come up with in the comment section.