Neighbor's cats pee on my balcony and furniture all the time. This time, my wife accidentally left the nice canvas and wood folding chair on the balcony and a cat snuck up and peed all over it.
So, I'm thinking, leaving out hot dog bits with ExLax hidden in it...
Something similar to the squirrel catapult...
Any other ideas? The crueler, the better. And preferrably non-lethal and quasi-legal.