High Quality Content by WIKIPEDIA articles! Michael Ryan Pritchard (born May 4, 1972) is an American musician, best known as the bassist, backing vocalist and co-founder of the American Rock band Green Day. While at school, he would play "air-bass." While pretending to pluck the strings, he made the noise, "dirnt, dirnt, dirnt". As a result, his schoolmates began to call him "Mike Dirnt".