"No-one knows for sure exactly how the residents of Tyneside or perhaps more accurately Newcastle upon Tyne became known as 'Geordies'. One theory is that it was the name given to the workers of the railway pioneer Geordie Stephenson, another is that it was a term for a pitman deriving from the use of Stephenson's Geordie Lamp."
Source: http://www.englandsnortheast.co.uk/GeordieOrigins.html
Selected words and phrases from the Geordie Dictionary.
Agyen: Can mean again or against.
Bonny Lad: Informal term of endearment or form of address 'Y'areet bonny lad? - 'are you well my good chap?' Address from one male to another usually to a younger male or one of similar age.
Mosstrooper: An old name for the Border Reivers.
Nivvor knaa noot aboot me neet oot: I can never remember anything about my night out.
Oilin' His Wig: Drinking heavily.
Unbeknaan: Without knowledge of.
Ye hev yersel a yall at yem : Chill and have yourself a nice relaxing drink of ale in the comfort of your own home.
Ye knaa wot, aw will.
Source: http://www.englandsnortheast.co.uk/GeordieDictionary.html