G'day is a shortened form of good day that has been a common informal greeting in Australia for over a century, with mate used widely as a friendly term for a friend or stranger. The clipped phrase became a shorthand for Australian speech in films, adverts and comedy, and later spread online as a meme sound. Short audio versions circulate on soundboards and in edited videos, where the exaggerated accent signals an Australian character, a laid back attitude or a joke greeting without any further explanation needed.