他和表弟从小就是形影不离的捣蛋鬼搭档。

He and his cousin have been ___partners-in-crime since childhood, causing mischief wherever they go.

我最好的朋友是我的捣蛋搭档，我们总是一起搞恶作剧。

My best friend is my ___partner-in-crime when it comes to playing pranks.