According to Lars, "the point is to advertise to people in the vicinity that [you're shotgunning]," and to get other people to join you. True, this seems desperate, and even a little pathetic. But you're definitely shotgunning with other humans (Red's magic number: six, which "makes a clean circle, allows for an expedited process, and makes for precise execution"), so... strength in numbers, right?
5. Bottoms up
The term “shotgunning” refers to the way the beer, driven by physics and magic, will blast double-quick into your mouth. And make no mistake: it will, ‘cause in one swift motion, you'll put the puncture up to your lips, tip your can vertical, and pop its top.
Here's a video of two Ann Arbor olds demonstrating this critical moment, because the Internet: