One who knows an alarming amount about the obtaining, handling and digesting of the male ejaculant.
Man Justin, you gobbled up that stuff real good. You have become a real jizz expert.
Long haired jizz expert- best seen in the tv show Workaholics, refers to one that has long hair and is an expert in the fields of seman.
Get away from me you long haired jizz expert!
Adam: No one talks to my long haired jizz expert like that!