Only friends share secrets. 只有朋友才分享秘密.
Just keep it between us. 我们俩知道就好了. Don't tell a soul. 不要对任何人说. We'll have to keep a lid on it. 我们必须保守这个秘密
Don't ever tell her this. 千成不要跟她提起这回事. Keep it under your hat. 不要把它说出去.
Don't let him know? He already knows. 别让他知道? 他早就知道了. I'll never tell. 我绝不说出去.