Crazy Carts are souped-up electric go-karts with rear wheels like the ones on the front of shopping carts. Some goofballs decided to turn a real car into a Crazy Cart by replacing the rear tires with caster wheels.
Their talk of taking it to the DMV reminds me of this classic scene in Planes, Trains, and Automobiles: "Do you feel this vehicle is safe for highway travel?"
Crazy carts are actually a lot of fun, but it's easy to lose control while turning. They have a few features to reduce the chance of rolling, but I'm not sure most kids are going to be making safe maneuvers in these. Here's what they look like:
Here's a pretty good demo: