An oil worn as perfume by dirty hippies in lieu of showering or bathing in any way. Used to mask the scent of marijuana and week old body odor, but usually it merely mixes with the scent to form a new, BO/Patchouli combo that can repulse even those who are olfactorally challenged, except for hippies, who love it.
Fred: I can't go to the war protest because of all the Patchouli oil. It makes me gag.
Hippie: Mmmmmmm, mm, mmm , mmmm. Is that sex I smell?