This sign is a source of great amusement to my children. It resides in the yard of a house we pass by on one of our many walks when at my parent's beach house. In fact, my kids will often insist we make sure to go by it. About three houses down from it, they start giggling and the giggles can sillier the closer we get.
What made me laugh even harder than they though, was Teresa's comment one time we walked by. She asked me why someone would want that in their yard...was it a decoration? I told her it was there because they didn't want dogs to poop in their yard. She gave a snort of disbelief and said "don't they know dogs can't read?!"