Throw for a loop.
Throw for a loop.
To "throw for a loop" means to surprise or confuse someone so much that they're momentarily disoriented. Picture watching a magician perform an unexpected trick that leaves you scratching your head, trying to figure out how it happened—that's the essence of being thrown for a loop.
He really threw me for a loop with that surprise party.
He surprised me greatly with the unexpected party.
The plot twist in the movie threw her for a loop.
The unexpected plot twist in the movie shocked her.
When Jack announced he was moving to Japan, it threw everyone for a loop; nobody saw it coming.
Jack's announcement of moving to Japan was a shock to everyone, as nobody expected it.