狐に小豆飯
Meanings
1
setting a fox to guard the henhouse; trusting a cat with milk
idiomatic expressionrare term
A rare proverb meaning to put someone in a situation where their natural instincts will lead to trouble, similar to 'setting a wolf to mind the sheep'. The literal image is giving a fox its favorite food, adzuki-bean rice, which it will inevitably eat.
See also: 猫に鰹節
This situation is exactly what they mean by 'setting a fox to guard the henhouse'.