When you see your mom come back from the salon with bright green spiky hair and your jaw drops to the floor in total shock, you’re flabbergasted. You are really, really shocked — pretty much speechless.
Use the adjective flabbergasted to describe someone who's astounded or surprised for any reason, good or bad. You could be flabbergasted at how astonishingly expensive a parking ticket is, or at how incredibly delicious pineapple pizza is. Flabbergasted has been used since the late 18th century, but no one knows for sure where it originated. The word sounds like what it means: when you say it out loud — "flabbergasted!" — it somehow captures the spirit of astonishment and shock.