Something extremely awkward, stupid, or embarrassing such as a person, animal, or action. A portmanteau word combining the words "legendary" and "derpy".
"That dog's face is legen...wait for it...derpy!"
"Tommy crashed his bike into a parked car. Such a legenderpy move."
ME: urban legendery swordypickaxe eeeeeeeeeeeeeeeeeeeee
ALSO ME: *hits my head26 times and calls the asylum on myself because i just realized what i have done*