How do I lease a new car if I have really bad credit?

Large cash deposit or some take debit cards.

Can you get someone to co-sign?

no. I wish.

Repair your credit and try again in a couple years.

Right now? PupnTaco has it right. Wait until the financial crisis has passed before you try again (and fix that credit in the mean time!).

Could this be why you have bad credit? In these questionable economic times, why not buy a car you can afford? Save the money you would have put toward a lease payment, and then buy the car you want.

Leasing is a very bad move financially.