10. Scooby and Shaggy were always being freaked out by ghosts and ghouls, but no-one else saw them before Scoob and Shaggy.
9. Scooby and Shaggy always had the munchies.
8. Shaggy always thought Scooby was talking and was the only one who could hear him and understand him.
7. Scooby and Shaggy always fell into the trap that was intended for the monster because they were tripping over themselves and couldn't see where they were going.
6. They were always deluded and warped and dressed up in costumes and entertained the monster/ghost
5. Shaggy always said 'like' to the extreme, e.g. 'ZOIKS! Like let's get outta here, Scoob!!' And what's a zoik, anyway?
4. Scooby and Shaggy were always the ones in the back of the van (doing who knows what).
3. They drove around in the MYSTERY MACHINE, which had that weird trippy design on its side.
2. Shaggy and Scooby were always giddy and laughing.
1. Look at Shaggy; the way he dressed, his goatee, etc., 'nuff said.