upper-lip valve

What you create when you place the mouth of a beverage-bottle whose contents you plan to finish right then under your nose, press it inwards lightly to form a seal, tilt your head back, and then slowly slide the bottle downwards so that its opening gets gradually exposed overtop of your mouth and you can thus guzzle the liquid directly down your throat; the trick is to keep your upper lip pressed against the mouth of the bottle so that you're still partially covering the bottle's mouth, and thus the drink glugs out slowly enough to allow you to swallow it at a comfortable rate until the bottle is empty.