Just a pet peeve, I hope I don't tell my kids it's "adults stuff" and leave it at that. I think kids can sometimes surprise you at how much they can understand. Explain it as simply as you can, and if they don't get it try again. If they still don't get it, well maybe it's too advanced for them, or maybe you can't explain it in a simple enough way.

I know I was eternally annoyed at how much adults underestimated me growing up.