They're great for Home Shows. Mine is a coupon for $100 off a Platinum Package.
I don't play the joke on the prospect, that starts things off on a negative vibe. I hand them to people unfolded and show them how they can use them on their friends. I tell them "Don't leave them laying around here as a joke because some big redneck will come beat my butt." They laugh and I give them two, one to redeem and one to play with.
I met a guy last week who still had his in his wallet. He shows it to people all the time.