bumreek 

The specific odor of a ripe homeless person, especially (but not limited to) a subway dweller in New York City. It is impossible to describe fully, but can contain any/all of the following: urine, feces, general body odor, filthy hair, lice, garbage, dirty clothes, grimy train smells and disease. Once experienced it can never be forgotten.

"I was really excited to find an almost-empty subway car at rush hour, only to discover (after the doors closed and we left the station) that it was contaminated by bumreek."

bumreek by FlavorDave April 22, 2006