Sauce = proof/source in 8kun speak.  Also "new fag" in the other reply to you is not an insult.  "Fag" is a catch-all term on 8kun.  Lawyer on the boards = lawfag.  Somebody who follows airplane stuff = planefag.  Somebody who's new = newfag.  This might help, if you're interested in more info:  https://www.lurkmore.com/view/History_of_4chan#Pre-History