You could probably phrase it like the non-cheque junk mail that I get. It looks like a cheque (for all I know, maybe it is) but there is fine print stating tha

You could probably phrase it like the non-cheque junk mail that I get. It looks like a cheque (for all I know, maybe it is) but there is fine print stating that if you cash this, then you sign up for a membership of some sort. IIRC, I've also seen "this is not a bill" junk mail that looks like a bill. I'd imagine that these are skirting close to the edge of the law as well.