What was the song 7 things about?

"7 Things" is a pop-punk song recorded by American singer Miley Cyrus that tells her about an ex-boyfriend that left for some blonde girl and the song is in form of 7 things she dislikes or hates in some blonde. The blonde that the song references is her older sister Brandi Cyrus after her former best-friend was romantically entangled with the latter.