Should I feel bad for keying my friends car really badly
Why would you do that to your friend's car?
Because he's got a really shitty car.
You shouldn't key someone's property. Once they find out it was you they will sue you for damages.
Haha, I'm not worried about getting sued.
Consider how you would feel if you found out a friend had damaged your car like that. You should probably own up to the damage and see what you can do to fix it.