“It's raining cats and dogs.” Today this expression means that it is raining extremely hard. This well-known expression dates back to the Elizabethan times in England. Thatched, slanted roofs were popular during this time period. Since pets were considered dirty, they would be forced outside and would actually sleep on the roofs. When it would rain the roof became too slippery to stay on and these cats and dogs would slide off and fall. An observer looking out of their wind