Someone who studies and specializes in the male organ.
A doctor that checks up on the testicles and has to look at someone's dick for eg diseases (STD's), or misshapes.
A plastic surgeon that specializes in operations to the male organ.
"Man, I had sex with this woman, and now I start to have a rash on my penis."
"Visit the Dickologist".
"My penis is too small; I can't pleasure my wife"
"I heard the dickologist at 49th street can lengthen it with a small surgery".
One who knows and understands the dick and is able to treat the dick EXACTLY as it desires to be treated.
One who gives good/great/amazing head.
The mistress of blowjobs!
Art: So, how's the head?
Sam: That bitch is a dickologist!