Anyway, last time I checked, this was the USA and we had so many of our own colloquialisms we didn't need to lift the prissy ones from across the pond to sound cosmopolitan.
It's a little like using the word "shedjewel" or maybe just dropping a little latin into your sentences as though it was something all the homeys do.
NO STOMACH for pretentious anything, esp. writing.
peace out.
And there is NOTHING "prissy" about "gobsmacked". It's a very working class term.
There is a difference between expressing oneself clearly and pretention.