"Alright Bob, you ready?" -readys pistol-
"yeah... Whoa wait a second Tim, they have a sign that says no firearms."
"damn it all! Well, looks like it's time to go home."
-How anti-gunners think criminals talk to each other before a stick-up
The problem was the owner was too cheap to buy a sign for both the front an back doors. If he had a sign on the back door they would have seen it, read it, and moved down the block to the shop that doesn't have the signs up.