It is a fun song I never got it outta my head for at least 2 days! And to me, it means that Bruno is in love with a girl named Who-knows-what-but-I-don't-think-its-Grenade who really hates Bruno, but he is so in love with her that he can't go away from her, and he will do anything, even "Take a bullet straight through his brain. Yes he would die for his baby, but she won't do the same."