Any message to order.
Have you considered an inscription in Runes or Tengwar (Elvish)? Apart from being more discreet than English, they are more easily explained away in vanilla situations. Elvish looks magical and romantic whatever you write in it.
This pretty design actually means "Fucktoy", but you wouldn't have any trouble persuading family or coworkers that it's an Elvish blessing or the name of the Woods Goddess.