すみにおけない
witty and knowing; not to be underestimated; smooth operator
Also written 隅におけない、すみに置けない
Expression
彼女かのじょは妻つま？あなたも隅すみに置おけないわねえ。
She's your wife? There's more to you than meets the eye.
あなただってなかなか隅すみに置おけないって噂うわさがあるけど。
I hear that you yourself are quite the smooth operator.