Answering anonymously in case the neighbour in question is on Quora.

We had an awful neighbour in the flat upstairs - she was noisy, seemingly nocturnal, and enjoyed moving furniture around and hoovering at 3am. Not only that, but anything we did that she didn’t like (coming home late, putting the bins out too early) earned us an unpleasant handwritten note shoved under the door or an awkward confrontation in the hallway.

We discovered a rat infestation while we lived in that flat; the kitchen units had been improperly fitted and rats were coming up from under the house and out into the kitchen via the cupboards. A pest control guy came and put poison down. Rat poison causes their bodies to dry out so that if they die somewhere inaccessible there’s no smell.

So one morning we got up after a disturbed night of the awful woman upstairs performing her own one-man version of Stomp in the wee hours to find a desiccated rat corpse in the kitchen. It was like a furry sock with a tail.

Anyway, we put it on her stairs. She came down barefoot in the morning and trod directly on this dried up rodent cadaver. Screamed the place down.