You will Watch The Grim Adventures Of Billy and Mandy Season 6 Episode 4 online for free episodes with HQ / high quality. Stream cartoons The Grim Adventures Of Billy and Mandy Episode 64 Modern Primitives: When Billy digs his front yard he finds a frozen caveman, who is actually Fred Flintstone (from The Flintstones), but whom Billy names Jake Steele. Then, Billy tries to acclimate Fred to the modern life but the job is not easy. When Fred is taken to school, he predictably goes out of control, kidnapping Miss Butterbean and running away in Principal Goodvibes car. The ensuing chase results in Fred crashing into an ice cream truck, becoming frozen again. Then, instead of reaping him, Billy decides to bury Fred in the yard again. In the end, a future is shown where both Billy and Fred are defrosted by brain-eating creatures.