English help please?

It’s sort of a translation, but like everything pertaining to language, it’s also a cultural thing. Perhaps there is an equivalent saying for it that I’m unfamiliar with?

There is an expression in Hebrew that rhymes, which is always more fun, which means something like this; if you are given something – take it; if you are being being hit (hurt); run; and if you are promised something; forget it (as in – forget about it – it won’t happen.

I was tooling around with it and came up with something like this; if you are given something ; take it. If you don’t have something; make it and if you don’t know something; fake it.

But you can either defer or refer me to something along those lines (perhaps in another language French, Dutch or whatever that you know) or attempt a similar rhyme expression.