A large brightly colored bottle used for identification purposes so that American students can find other American students while abroad. Other uses include the transportion of liquids.
Someone who claims to possess or actually possesses a tremendous knowledge of the wilderness and has a well-traveled plastic water bottle - usually with stickers from various outdoor locations.
That dude was telling me some amazing stories about his six month backpacking trip in Patagonia. He such a nalgenius. And that BPA-free water bottle of his is sick - did you see the wear marks on it?