@preparedwombat got it right - it's a spout for old oil cans.  

In the bad old days, motor oil came in wax-coated cardboard cans with metal lids, one would jab the spout into the lid to puncture it, and pour out the oil.  I actually have one of those old oil cans, which is how I figured it out.  The previous owners of my house left lots of interesting stuff behind - including insecticide that actually *works*, but I digress...