Excerpt from this article:
Anyone who’s ever had an office job—or, come to think of it, a life—is familiar with the “nudge,” the email you send when you need someone to do something for you and that person hasn’t responded to your first request. So you send another one. And even though you phrase it as politely as possible, both parties know exactly what it is: It’s a second notice. It’s strike 2, as in one more and you’re out. Even the word we use to describe these actions, and sometimes in the emails themselves, nudge (“Just wanted to send a nudge on this!”), attempts to put a gentler name on what is at heart a demand.