1. Phrase used to question the wisdom of a smartass trying to pass off infomation on a topic you know the person knows little or nothing about.
2.Can also be used to change the subject.
Versatile phrase used as a put down.
Guy 1: I think I need more fiber in my diet because I only shit once a day and my ass bleeds.
Guy 2: What are you an assologist? or
What are you a colonologist? or
What are you a fiberologist? or
What are you an assbleedologist? etc.