Son: Mom, they need to make a car that drives itself so you can drive places. It would know when to stop and to pass cars and everything.
Me: That would be one expensive car. I'd never be able to afford it if they made one.
Son: Well, they should make something for people so they could drive.
Me: Actually; they do. It's called a Hummer. That way you go over things instead of hitting them when you have a seizure. *feeling pleased with myself for the joke*
Son: *pause* Can we get you one?