Can have a variety of meanings, but it mainly means to be without something, or lacking something. Here are some words that bald can easily replace: ugly, poor, stupid, broke, etc.
Yeah, I can't go out tonight, I don't have money, I'm bald.
Tina: Yeah, that boy from my Physics class asked me for my number...
Me: Did you give it to him?
Me: Why? He's so bald! And so are you for giving it to him!