The homeless poop out of the elements. When I was growing up in Chicago, we always knew to stay out of the last "L" train car on a trip downtown because when it got really cold, the bums would pay the 10 cents (or jump the turnstile) and use the train to stay warn all night. And even though they were bums, they had a code. Much like White Goodman, "Don't crap where you eat." So the rear car of any train was always the "poop" tube. Bums also like to use Wal-Mart, and if they are true homeless, check out the steaming piles on the sewer grates around town…except for you losers in warm climates.