Flabbergast (flăb’ər-găst’) means to overwhelm with wonder or surprise. If you are flabbergasted, you are astonished with something.
I’m flabbergasted — never has my flabber been so gasted! (Frankie Howerd)
You, too, can make turkey chops at home and flabbergast your guests, but first you have some obstacles to overcome. (NY Times)