Trust is a wonderful thing. When you reach that level of friendship and understanding with someone then it can give you a nice, happy, tingly feeling in the pit of your stomach.
Or a pain in the side of the head. You choose.
If someone, however well you may know them, suggests that they kick a can off the top of your head, always turn down the opportunity. Positive thinking is great, and saying yes to new experiences is also great, but there are limits.
Not only does the guy with the can on his head get booted in the side of the face, the guy doing the booting falls over, so they both end up looking like complete and utter twonks.
Still, it serves them right, I suppose, because they are complete and utter twonks.