I can't think of one that could be considered "the worst", most pick up lines fail with me, I laugh hysterically and then I walk away. But recently some dude in Wal-Mart, near Valentine's Day, was like: "Damn Mami, you fine, you wanna be my valentine?" Uhhh, No.

Honestly, it's different for every girl. Confidence is still a pretty good one. It's the sexiest thing a man can posses, not to be confused with egoism. If the girl thinks she's too good for you, you're too good for her. Remember though that rejection doesn't always mean it's you. She might already be interested in someone else or just not looking for a relationship.