Ah, the Ghostbuster pack! My shop had a pair of these. They're kind of gross--hard to clean, don't keep things hot for as long as you would think, and the whole "5 gallons sloshing around on my back all day". But at the same time, they're kind of awesome if you're using them at some kind of event where it's okay to look ridiculous--parades, festivals, and so on. We would dress people up in coffee sacks and send them out into festivals to give free samples, to draw more people into the cafe... No idea where we got them from.