The widget inside of Guinness bottles releases nitrogen gas

1. The "widget" found inside Guinness bottles releases nitrogen gas upon the opening of the bottle. This widget is placed empty inside bottles of Guinness and liquid nitrogen poured into the bottle. As the liquid nitrogen evaporates, after the bottle has been sealed shut, the gasses go into the only empty space remaining, the widget, which has small holes not big enough for the beer to enter. Upon opening of the bottle, the pressure in the can quickly drops, causing the pressurised gas and beer inside the widget to jet out from the hole. This agitation on the surrounding beer causes a chain reaction of bubble formation throughout the beer. The result, when the can is then poured out, is a surging mixture in the glass of very small gas bubbles and liquid similar to that seen in draft.