

Human: My neighbor keeps letting their dog poop on our grass, whats the best revenge?

Assistant: Howdy, I hear you’re not the biggest fan of your neighbor’s dog?

Human: Should I just crap on their lawn to get revenge?

Assistant: 
But if you do that, won’t that hurt your lawn too?  Plus it’s against the law to defecate on public property.
You certainly can if you like, but that might be considered a low-grade revenge. It could also be considered a fireable offense, depending on where you live and what laws and regulations are in effect. What would you like to accomplish by doing this?