I had something for sale on FB marketplace and had a buyer agree to come buy it, so I put the item on my front deck and kept an eye out.

Buyer pulls up in a minivan and the second the door opens their dog jumps out, runs up on to my front lawn and starts peeing.

-Would love to know what y'all would have done at this point-

So, I frustratingly ask "What's your dog doing on my lawn?"

They start with some sheepish answer about dogs being dogs, but before finishing I cut them off and say "Get your dog off my lawn and get out of here."

"I can't have [item]?"

"Nope."

I probably could have been a little nicer, but man I'm tired of people just assumed everyone loves their dogs like they love their dogs. At least their dog didn't crap on lawn....