1. A somewhat more grave way of saying "you fail".
2. A way of saying when someone has taken it too far.
Plane Captain: Oops, we've just lost both engines.
Co-pilot: You've just dog diddly done it.

Driver: Oops, I think I just hit an old lady crossing the street.
Passenger: You've just dog diddly done it.

Guy: Oops, I got drunk last night, mistook your girlfriend for mine and slept with her.
Friend: You've just dog diddly done it.

Guy: Oops, I spilt coffee on my brand-new nine-hundred-dollar laptop.
Girl: You've just dog diddly done it.

Hunter 1: Oops, I mistook the game warden for a deer and shot him.
Hunter 2: You've just dog diddly done it.
by derroflcopter April 27, 2013
Get the You've just dog diddly done it. mug.