Examples: 1.You just floored me [ amazed/shocked me] when you told me that you and your wife had separated. You seemed to be the perfect couple. 2. I was totally floored [ astounded] when I won the lottery Another slang term Australians use for "being floored" is "being gobsmacked" Example: I was gobsmacked when I heard about the cyclone

You were so surprised you were knocked down to the floor! :) Good news or bad news, they'll both have the same effect.

Hi, it means kind of like "to be totally shocked" by something. eg. your friend tells you something really bad, and it "totally floors" you. it is def. english slang/idiomatic expression, but a good one!