One of the rarest substances on Earth. Is most often produced when a hippy is pulled over by "the man". There was an unconfirmed report that hippy sweat had been distilled from a working hippy. However most experts agree this is unlikely.
Hippy stench is commonly mistaken for hippy sweat. The former results from the hippy's inate fear of bathing and is of a gaseous form, while the later is produced through physical exertion of the hippy (hence it's rarity) and is in a liquid state.
After 40 years of trying, Ben & Jerry's gave up on their effort to produce hippy sweat flavored ice cream due to their inability to harvest the natural flavoring.