Appliance repair people: what's the grossest thing you've found in a clients appliance?

Once I had a tenant complaining of a weird smell from their oven. Sure enough it smelled like urine. I've seen rats nests in ranges before (they build them out of the insulation), but when I opened the bottom they were no signs of rodents, or urine. So when I opened the actual oven I saw a puddle at the bottom. When I pointed it out, the tenant called out her roommate. She admitted she came home drunk the night before with someone she met at a bar. He was acting weird, so she told him to leave. He went into the kitchen for a while, and then finally left.

He pissed in her oven.