I cannot find it now, as all the search terms have been poisoned by spamming porn sites, but there was a post by a US escort on this a few years ago. As well as what Violette mentioned, the thing I remember was using the word "daddy". Ewww, but it worked for her. Apart from that one, I found her list hysterically funny.
Encouraging them by word and deed to fuck you harder and faster, in a position where they can see what's happening, will also work with lots of men.
Faking it is an option, but you risk them thinking what they've been doing works. That doesn't help you if you see them again or any other partner.
Although it is possible to fake ejaculation, I am glad not to get these sort of clients. There are ones who want me to orgasm, but they are ones who are prepared to listen and do what will work, rather than the "if I fuck for long enough, they will come" ones.