Scooby-Doo is just a normal, popular kids television show, right? WRONG. Scooby-Doo is a drug-induced cartoon and is very fantasy-like. Shaggy is a hippie-high school dropout who spends most of his free time getting high up on drugs. Scooby Doo does exist, but he doesn't talk. It's the hallucination. Scooby and Shaggy sat in the back of the Mystery Machine because they would smoke weed back there. Thus explaining why when the Mystery Machine took off, smoke came out of it. As for Scooby Snacks, they are drugged up. This explains why Scooby and Shaggy get more courage after eating them, simply because the drugs kick in. Shaggy and Scooby eat a ton, and it is a cause of the munchies. Scooby also earned the nickname "Scooby Dooby Doo" from all the doobies, or joints, he took in. Also, in the movie, Shaggy eventually falls in love with a girl named Mary Jane. Mary Jane is quite synonomous to marajuana.
But what about the rest of the gang? Why do the jock and popular girl hang out with the nerd and the stoner kid?
Well, Fred and Daphnee are a couple from the popular gang. But they didn't care as much about getting popular as they did getting high. And the gang gets drugs because Velma messes with the chemistry of growing weed, Shaggy will stop at no costs for getting some, Daphnee has tons of money being rich, and Fred being the leader of it all. Also, Fred and Daphnee are sex-addicted. They secretly go off into the Mystery Machine to exhange into strange sexual acts while Velma, Shag, and Scoob go together in the complete other direction.
And what else about Velma? Alot of people think she is a lesbian, but truth is, she hangs out with the gang less for the drugs, more for the dog. Scooby. She is zoosexual, meaning she is attracted to animals. She did sexual things to Scooby while the others weren't looking.