Shotgunning is a means of consuming a beverage, particularly beer, very quickly by punching a hole in the side of the can or cup. A related technique, strawpedoing or snorkeling, is used for containers not easily punctured such as a glass bottle. A straw is inserted into the bottle to similar effect.
The technique works since a literal bottleneck is created where air entering the container to release pressure must travel through the same orifice as liquid leaving. The extra holes allows air to enter simultaneously as liquid leaves the main hole.