"Excuse me, I'm Dr. Bringdown!" — Dr. David Bringdown[source]
Dr. David Bringdown is a mad scientist and a member of L.O.V.E.M.U.F.F.I.N. (The League Of Villainous Evildoers Maniacally United For Frightening Investments in Naughtiness). This evil scientist has a monstrous right hand. His name is in reference to an insult by Rodney directed at Doofenshmirtz because he was "bringing down" his plans because he mentioned a flaw. And when Dr. Bringdown states that it's his name, Rodney responds, "Put a sock in it, David!!"