Sleeping policemen

Aha! Now I get it! What American's call speed bumps the Brit's call sleeping policemen. *Slaps forehead*.

It has just occurred to me that one of my first American guests will be arriving in less than a month, so I must prepare (or rather prepare them  for some....differences).

This is one of the first signs I saw upon my return to England, I will admit that here in the street my maturity level dropped to Zero as I snapped this photo after having a good chuckle.

For the record Americans call sleeping policemen, Sleeping policemen and they are usually caught napping in their squad cars. :-P And actually I want to know how this term "sleeping policemen" came about. It's not as though bobbies went about throwing themselves on the ground in order to slow traffic right? So where does it come from???