I'm bored, and here are some lame lines that were in my head:

"I know you are but what am I?"
WORST comeback line ever. If you want something as a last resort, never use this, it's pathetic. Sure, using it ONCE in a lifetime is fine, and probably a very nice comeback when you're in the worst of a cat-fight situation, but never use this more than once.

"Girl, do you have a map? I got lost in your eyes."
WORST pick-up line ever. This line went stale 2 decades ago. Try using this if you're gonna pick up a 50 year old chick (I highly doubt they'd even be flattered).

"I owe you one."
WORST line to use as a thank you reply. Never use this unless you know that you WILL be able to return the favour, otherwise, you'll end up like Chuck & Larry.

"You can do it!"
WORST encouraging line ever. If you use this when someone could do it, instead of encouraging it, it would just cause them to lose focus instead of gaining it (way to go).

"So what?"
WORST line to say to me. Let's just say I had some jam with the dude who said that, now the line not only is lame when you want to disagree with the odds of something, you earned yourself a knuckle sandwich from yours truly :)

Okay, so now you know what lines which are lame to me, don't use it on me, kthxbai (p.s. I think kthxbai is lame ;) )