Having recently extended my house, I now have a patch of gravel where once there was tarmac. Next door's cats (five I believe) think it's a litter tray.
I don't mind the cats themselves - they get out of the way as I reverse and I haven't squashed one yet - but after a week there was a whole supermarket carrier of shite to clear up and gravel strewn everywhere.
I bought a bottle of smelly green gloop and spread it over the gravel once cleared and tidied. The local pet store recommended it but I cannot recall the name and have thrown away the empty bottle. So far, six days and no turds.