This is an idea from the Wanted Bomb; and even though I knew of this joke before hand, Home (the movie) gave me the idea.
Lars and Padparadscha were talking together while the others carried on a conversation themselves. He has been getting more and more accustomed to her timing and takes delight in talking a serious conversation with her on occasion. But he wanted to try something.
"Hey, you wanna hear a joke?"
A few seconds pass and she says, "Lars would like to laugh with me? How delightful!"
"Haha! Yeah, it's a knock, knock joke. I'll say 'knock, knock', you ask 'who's there', I'll say the 'Interrupting Cow', and finally you'll say 'the Interrupting Cow who'." Lars paused for a half a second breath, "You wanna try?"
"The sequence sounds funny already!" Padparadscha replied after a moment, and then resumed two seconds later, "Yes, we should begin!"
"Alright. Knock, knock."
"...Who is there?"
"The interrupting cow." Lars waited approximately two seconds and a half before shouting, "Moooo!" He waited another second and a half to do so again, "Moooo!"
"...The interrupting co-" she stopped as if cut off by someone speaking over her. "Oh, I was inte-" she stopped speaking again abruptly. She began to giggle, "Oh, Lars, I've seen the most amusing vision between us! You, as the interrupting cow, have interrupted me to fulfill the joke! What a funny sequence!"
Lars felt accomplished having achieved that joke without messing up and making a fool of himself. They both laughed together in happiness before resuming a different topic to talk about.
