Paul Walker's Brain Matter

Alright listen up, chucklehead. This joke implies Paul Walker wasn't smart at all. The "brain matter on his dashboard" bit is a dark reference to his tragic death in a car crash. It's saying his brains were splattered all over the dashboard because of the impact. Walker was known for the "Fast & Furious" movies, which had a lot of car stunts and stuff. But guess what, genius? Reality ain't no movie, and car crashes are bad news.