Rotate box by pushing it

Hi devs, I got a big problem, which is probably tiny for you.

My problem is, I want to rotate left the box, when I push it from the right side. It can be a headbutt action just like SuperMario. How can I nail this box onto the scene and make it rotate whaen I hit it. What joint should I use? Do I need to writme some script?

Please help me.

Thanks

Your answer can be found here:

http://unity3d.com/learn/tutorials/modules/beginner/2d/hingejoint2d

Good luck!