The extreme discomfort/cramping/sweating associated with the overindulgence of too many hot wings (or other spicy food), too much cheap beer, or a combination of them both.
John missed football practice because his furnace ass kept him in the bathroom all afternoon.
by PR Gal 60010 February 17, 2009
A romantic partner who gives off a lot of body heat.
Wintertime camping is easy and comfortable when you share a sleeping bag with a furnace ass.
by EvilRedhead October 09, 2014