get cold feet
US /ɡɛt koʊld fiːt/
UK /ɡɛt koʊld fiːt/
1.
to suddenly become too frightened to do something you had planned to do
:
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He was going to ask her to marry him, but he got cold feet at the last minute.
•
I was going to try bungee jumping, but I got cold feet when I saw the height.