I’m guessing that the practice of shotgunning a beer is as old as tailgating itself.  The first time I saw this done was John Cusack in The Sure Thing.  Since then, I’ve participated in the age old ritual more times than I wish to remember.
I’ve never been so good at science so really cannot explain the physics behind it.  In order to properly shotgun a beer, you puncture the side of a full beer can, near the bottom.  The shotgunner places his/her mouth over the hole and tilts the can …