Questionable signage

On the way home from the hospital we go past an adult store called Naughty but Nice (which, as an aside, is a quite startlingly bright yellow), and yesterday I noticed that there is some rather appropriately inappropriate signage on the front of the store. In big red letter on what looks like it should be the front door, is written “Entry at rear”.
I got a photo of it so you can see for yourselves.
For any kids reading this, if you don’t get the joke, that’s probably for the best, and your parents will explain it to you when you are older (or maybe not)…