Take every credit card offer you get in the mail, fill them out and send them in. Then run every one of them up to the max buying whatever you want and then refuse to pay them.
We hired an employee one time as a trainee. We went to get him an American Express card and he had a FICO score of like 3 or something. The company had to co-sign. He screwed us but good when he left. He ran up the card and left us with the bill. His boss said it would ruin his credit. Not anymore than those two repoed cars.