감 떨어졌어요. (lost your touch)
감(感) [n] feeling, sense, a feeling or thought about a certain thing.
떨어지다 [v] to fall or drop
casual: 감 떨어졌어
>> This expression is used when the speaker feels that the hearer’s ability to grasp a situation has deteriorated a bit and they have lost their touch about something
>> “감” is a feeling or sense about a certain thing, and here it’s used as an ability or sense to intuitively grasp a situation without being told
>> “감” is also the Korean word for persimmon, and the same expression can be used literally when a persimmon has fallen off a tree