Sex vouchers or sex envelopes?

I'm just making a few sex envelopes up. They will say things like ' Tonight when you arrive, before you answer any of my questions about your day, you take me and whisper into my ear that you need an orgasm right now'. The thing is I do not know when she might use it. That is up to her.

I'm just wondering if anyone else has ever made sex vouchers or sex envelopes? What did you write on them?