The old man in Harry Potter.. a.k.a DumbleDor...
"All right you old Dumble Dick"
An odd-shaped dickhead that comes to a point resembling a wizard hat. When you take lots of drugs, your own cock will resemble a dumble dick. Thus, you can dumble dick someone if you have a pointed cock or if you are really fucked up.
I got dumble dicked at dead baby field.