Korean Four-Character Idioms
이심전심
以心傳心
Word for word
“passing heart to heart”
What it means
Understanding each other without words.
When you'd use it
Old friends ordering the same thing without asking.
Example
말 안 해도 아는 거 보니 우리 이심전심이네.You knew without me saying it — we're on the same wavelength.