I saw this sign at a shopping mall food court a few weeks ago. It managed not only to contradict itself (is it an exit or an entrance?), but also to contradict available evidence, as the door was ajar at the time—with no alarm. About thirty seconds later I saw a janitor carry some cleaning supplies “out” through the door as if he were returning them to a supply closet.
And on a related note:
This probably won’t be funny across the pond, but here in the US the “first floor” is the same as the ground floor. If you leave the first floor using the stairs, you’re not getting out of the building!