Luckily, my apartment is small, so heating it isn't a horrendous burden (I say now, before I start getting my real winter electric bills). But, of course, they asked how I manage to keep warm at night.
"Simple," I tell them. "I invested in mammals." 
You try being cold when you have a sumatran rat monkey curled up under the covers with you, not to mention two medium haired kittens curled up under your chin. I'm glad I invested when I did.
