Similar to nerd, except it refers to anybody who puts a bunch of rubber ducks right behind the front windshield of their car.
Dumbass A: "I put rubber ducks on my car!"
Dumbass B: "You're a Derd"
The mixture of a nerd and a dork. If you've been called this then it means you're both smart and weird.
Ugh, that's the derd table. They're too smart, but ew look that one is so weird too.