Checked out a very amusing site called Gimcracker and was prompted to write:
I am gobsmacked that 'gobsmacked' was successfully exported to the US, and thought that most US folk would follow 'collector of gnomes' usage. A quick poll of an American and half a Canadian suggested that 'blown away' or 'bush whacked' would more appropriate to North American colloquialities.

gobsmack - (OE) is actually a Scottish verb used to describe a form of greeting normally reserved for an challenger or rival. In ancient times 'gobsmacking' was often performed by slapping someone with a metal gauntlet. Early colonialists subsequently used the phrase 'thou givest the glove' which has now been shortened to 'giving the finger'.

God smack America