Quote Originally Posted by oldboy
Dude 1: Hey man, I saw you weren't in class today. I took notes for you.
Dude 2: Thanks man. Good looking out!
What 'good locking out' means in this context?[/quote]

Okay, yes, you're right, that's what it means here: thanks for looking out for me (worrying about me). But it's a very slangy way of saying it (that I've never heard). It's probably something teenagers say.