When something extremely important happens to you.
{person 1} : hey are you free for dinner tonight?
{person 2} : sorry, I have something very important to do. You know 09!
This is a variant of faggot, but with a twist to give the word rythem.
Dick: Hey Jimmy, what up!!
Jimmy: Shut up flag bagger 09!
Dick: WTF......
Jimmy: thats right, you'll never know what i daid and i can't get in trouble either!! HAHAHHAHAHAHA! Flaggot!!!