throw someone for a loop
/ˌθrəʊ ˈsʌm.wʌn fər ə ˈluːp/idiom
to surprise or shock someone so much that they feel confused
огорошить, выбить из колеи
Русский аналог: «огорошить; выбить почву из-под ног»
Американское, разговорное. Часто в пассиве: I was thrown for a loop.
“The news about the merger threw everyone for a loop.”
“His sudden question threw me for a loop.”
“I was thrown for a loop when she said she was leaving.”