A hipster who tries so hard to be hip that they act derpy all the time.
That guy wears plaid shirts with purple pants. What a derpster!
One who derps. DERP!!!!
1. Tom: "Dude, Gary is totally hitting on his girlfriends mom right in front of her!"
John: "What a friggin' derpster!"
2. "Bernie just screwed me on my car loan. I'll get that derpster if it's the last thing I do!"