man-to-man talk
He's a coward. He can't have a man-to-man talk. / Он - трус. С ним невозможен мужской разговор.
Excuse us for a minute, ladies. We're going to have a man-to-man talk. / Дамы, извините нас на секундочку. У нас сейчас будет мужской разговор.