WATCH: Friday is online hit
A 13-year-old American girl has become an internet sensation after her parents paid for her to record a pop song.
Rebecca Black's song, Friday, is all about looking forward to the weekend and having fun with your friends.
Eight million people watched Rebecca's music video online in the first four days after it was released.
And on Monday Rebecca's song was at number 25 in the US iTunes chart - that's four places above Justin Bieber's Never Say Never!
Friday was written for Rebecca by Ark Music Factory, a Hollywood firm that offers parents the chance to turn their kids into pop stars.
FRIDAY: THE LYRICS
"Yesterday was Thursday, Thursday, Today is Friday, Friday, Tomorrow is Saturday, And Sunday comes afterwards"
But lots of people have slammed the song as the worst piece of music they've ever heard.
And Rebecca has received lots of nasty comments on social networking sites.