Have you been sneaking around with him the whole time?都是和他出去鬼混了，是吗

sneak around鬼鬼祟祟

What are you sneaking around here for?

你在这里偷偷摸摸地干什么。

I had to sneak around and hide my smoking from my parents.

为了抽烟我必须鬼鬼祟祟地躲开我的父母。

Don't lie to me!别骗我

lie to对 ... 撒谎

Least of all would I lie to you.

我最犯不上对你撒谎了。

Don't lie to me--you knew damn well what was happening!

别对我撒谎你完全知道事情的真相！