Not really silly signs, but more the users well readers of the signs that are silly.
We got three shops in a row from the left - relish/jam shop, antique shop and then the bike shop I work in. To enter the antique shop you have to enter from the relish/jam shop, not the bike shop. If you look into the antique shop it is rather easy to spot the the hole in the wall to the left of shop into the relish/jam shop and that there is no hole in the wall to right into the bike shop.
Every month for the last seven-eight months the relish/jam shop owner have tried a new way to let customers know how to enter the antique shop. "Please enter shop via shop on the left", "Please enter shop via the relish/jam shop" etc - with and without arrows and the bigger and bigger sign on the door*. Every market day we have a least 2-3 people walking into the bike shop trying to find the none existing hole in the wall to the antique shop**.
Along with many people outside doing a little dance from the left to the right, trying to figure out if the shop with 6-10 bicycle outside and many more in the windows is the relish/jam shop, where the dead give away is the name above the shop and the jam/relish jars in the windows.
* Which many people don't even see, along with pile of antiques on the inside of the glass door, blocking the possibility of entrance through that door.
** It is rather funny when we got a "train" of people walking into the shop following the leader who walks straight into the wall full of helmets on display, before they figure out that there isn't a hole in the wall which they can enter the antique shop by. And then you have this queue of people trying to figure out where the exit is, we just need a bit of Benny Hill themed music and we are onto a classic