The actor was just 10 years old when he won the part of Ron Weasley in the hit wizard franchise, and it was a homemade video audition which convinced producers to give him a starring role.
During an interview on British chat show Justin Lee Collins: Good Times, the 20 year old tried to avoid performing the piece, admitting, "I can't remember it. I don't have a beat, I need a beat."
But host Collins convinced the actor to reproduce his audition video.
Grint rapped, "Hello there, my name's Rupert Grint, I hope you like this and don't think I stink", before confessing: "That was the first line and all I can remember. I was 10!"