Another name for a woman's ass / sphincter depending on the reference. A faucet is a regulator for controlling the flow of liquid from a reservoir, in this case the reservoir which is holding the feces (aka poop) is the woman's anus and the sphincter is the faucet ergo feces faucet.
Man 1: dude, that broads feces faucet was so tight last night when i plowed her doggy style.
Man 2: nice bro
Man 1: check out the feces faucet on that broad, id love to tap that
Man 2: man i know, that is one nice booty. one of the nicest i have ever seen.