Michael Ryan Pritchard (born May 4, 1972) is an American musician, best known as the bassist, backing vocalist and co-founder of the American Punk rock band Green Day. He has also played in several other bands, including The Frustrators. During grade school, he would constantly play “air-bass”, and while pretending to pluck the strings, he made the noise, “dirnt, dirnt, dirnt”. As a result, his schoolmates began to call him “Mike Dirnt”.