Flabbergasted - To be surprised, amazed, or shocked very unexpectedly

Lucille was flabbergasted when she arrived at her classroom Tuesday morning for another day of teaching, and her 4th grade students had made a surprise birthday party for her.

When Joe went to pick up his car from the car mechanic, he was flabbergasted when he was given a bill for $2300 for what he thought was a routine repair.

When Fred and Martha Smith saw how much the flood had damaged their basement, they were flabbergasted.