My microwave LOL
I was cleaning it with vinegar (boiling a cup of vinegar in it) and it sparked out the back and made a big pop. It smelled nasty. I'm lucky my kitchen didn't catch on fire.
I had the great idea of trying to do without one (I've been rolling this around for a while) until my daughter came down asking for her Friday night popcorn to go with her Friday night movie. SNAP! I actually went to the neighbors to ask them to pop out popcorn for us!