A beer bong consists of a funnel and a length of hose, typically long enough to build up some good pressure on the beer at the bottom. It will introduce a large amount of alcohol to your system very quickly, and, depending on your tolerance, will get you drunk. TKE's a good place to find one.
WARNING: Do not try to drink anything dark with it, as one won't get very far that way. Stick to Keystone Light, folks.