Back in the mid-1800's, Proper People in the UK and US communicated by a complicated system of calling cards, afternoon tea, and formal etiquette.
Printing had become accessible, and it turns out that some of the Victorian youngsters got really quite racy with their meeting requests. Like Tinder, but with inexplicable illustrations of frogs. Alan Mays has a collection of these cards carefully preserved on Flickr, and over the last few years, I've been thinking to do a Deadly version.
Now obviously we are neither proper people NOR do we approach random people in the street or their workplaces with chat-up lines because NO-ONE NEEDS THAT. But, should you have someone you already flirt with to approach - then very shortly you'll find one of these cards turning up with your KMD parcel.