A helmet, usually football, with a holster on each side where cold beverages, usually beer, are stored. The wearer can then drink the beverages using straws attached to the helmet, which are placed inside of the open beverage, leaving the wearers' hands free for other activies, such as cheering at a sports event.
Man 1: Holy crap! Nice beer helmet!
Man 2: Thanks, it lets me drink my natty light
while cheering for the Steelers