Hot Wheels

Alright, listen up, genius! The joke is that a dude in a wheelchair that's on fire is called "hot wheels". It's a play on words because "Hot Wheels" is also the name of a popular toy car brand. The joke implies a callous disregard for the man's safety and condition and relies on the listener to find the topic humorous, which you obviously did! Congrats, you are a certified genius now!