My father used to chide us children with “don’t play” — literal translation of the Tamil phrase “விளையாடாதே!”. It’s perhaps more accurate to translate it as “be serious” or “don’t be irreverent”. I prefer “don’t play”. It’s a familect. But, it’s also a beautiful assertion of the fact that sometimes made up words say a lot more than existing words can.
Whether you’re writing fiction or non-fiction, you must feel free to adapt these delights into your work. You don’t need to write it entirely in a slang, like Scottish novelists spectacularly do. Or even restrict it to dialogue, like it’s the appropriate way to do it.
I say use it like it’s correct. Say “don’t play” like it’s proper and see how it goes. Ken whit a mean? 🙂