Joke analysis

A grave robber and a cat napper walk into a bar.
The bartender, drying a shot glass with a small white dishtowel, looks over towards them.
“Hi mom, hi dad,” she says.
“What’ll it be?”

(Speaker shakes gadget (not a euphemism) and it finally starts working, projecting a PowerPoint slide, showing the text of the joke in Comic Sans onto the large screen on one side of the stage, while making a disconcerting buzzing sound and a small wisp of smoke rises from its insides, so small you are not sure whether you really saw it or not.)

Speaker: “Why is this joke funny?”
Speaker: “Because it is really funny if you know us. By ‘us’ I mean my wife and me.”
Audience member: “You mean ‘my wife and I’.”
Speaker: (Fires bolt from small crossbow at audience member, bolt glances off audience member’s backpack, tangles in beard of second audience member sitting behind them.)
Speaker: “No.” (And to person with crossbow bolt tangled in their beard.) “Sorry about that.”
Speaker: “See, we’re going to a ball later this month so we were taking a refresher course because I forgot how to dance. And one evening my wife was early so she window-shopped and noticed how expensive jewelry made of stags’ teeth is, which gave her the idea to exhume her grandmother, whose funeral she had organized and whom she had had interred with earrings intact because relatives had been arguing about who should take possession of them.”
Speaker: “Which idea matched the legal definition of grave robbery, according to our legally-trained daughter.”
Speaker: “And a week or so ago our tuxedo cat disappeared, pitching us into sort of a Schrödingerish state where we try to imagine she adopted one of our neighborhood’s 4 (at a minimum) cat ladies (the way she adopted us as a kitten), and is sleeping on a pillow and drinking cream, and try not to visualize her dead in a ditch. Lucky for us, the former is a very realistic scenario, because our other cats have for years come in from nights out, warm, fur brushed and smelling of woodsmoke.”
Speaker: “And so I tried not to think about her too much and thought I was adjusting well to her absence and being a grown-up about it until one night my wife and I were driving home from the train station or whatever and roughly in front of the doctor’s office in our village I said, ‘Stop! Stop the car!’ And she did, and I got out and crossed the street because I had seen a little black and white cat in the shadows. And it marched right up to me. I petted it, and it lay down and I picked it up and it meowed in a friendly way and I carried it over to the car and got in.”
Speaker: “‘Look who I found!’ I said. I was so happy, sitting there holding our cat. The relief I felt made me conscious of how I’d missed her. My wife pulled back out onto the street, but also took a closer look at the cat. ‘That’s not our cat, honeybunny,’ she said. ‘Oh,’ I said. ‘Are you sure?’ She pulled back over to the side of the road. ‘You have to let it go.’ So I let it go and it went about its business and we drove home hoping there had been no witnesses and that video evidence of my attempted crime wouldn’t be posted to social media.”
Speaker: “So that’s why the joke is funny.”
Speaker: “Thank you for attending my TED talk.”