입밖에 내지 않을게.

A: I need to ask you about something on the down-low.
B: Don’t worry. 입밖에 내지 않을게. What’s up?
A: What does your gut tell you about Bob?
B: I can’t put my finger on anything specific, but he’s odd.

A: 은밀하게 너한테 물어볼게 있어.
B: 걱정마. I won’t breathe a word. 무슨 일이야?
A: Bob에 대해서 솔직히 어떻게 생각하니?
B: 뭐라고 구체적으로 딱 꼬집어 말할 수는 없지만, 좀 이상하지.

[Additional expressions]
*I need to ask you about something.
– I have question for you. / I want to get your opinion about something.
*on the down-low
– secretly / just between you and me / without anybody else finding out about it
*Don’t worry.
– Don’t sweat it. / Don’t give it another thought. / No problem.
*I won’t breathe a word.
– I won’t say anything to anybody. / I can keep a secret.
*What’s up?
– What’s the problem? / What’s on your mind? / What’s bothering you?
*What does your gut tell you?
– How do you feel down deep inside? / What are your instincts saying to you?
*I can’t put my finger on anything specific
– There’s nothing I can be exact about / I have nothing certain
*He’s odd.
– He’s a bit strange. / He’s something of an oddball. / He’s not quite “right”.