You get a strip of paper and fold it into three. You cut the two thirds at the sides in half horizontally. Then you write stuff on them or draw pictures or whatever. Here's the front of the one my daughter found:
Translation: "Kellog's Corn Flakes" "The tastiest breakfast food!". Yes, I know I mis-spelled KELLOGG'S...
Here's the back:
Translation: "Fison's Fertilizer" "Kills weeds and makes flowers grow" and "Persil Washing Powder" "Keeps your clothes smelling fresh".
When you make it, you can flip the flaps over and create amusing combinations:
If you like, you can do a second set of panels and put them on the other side to the first set. I didn't do that here because the paper I was using wasn't all that thick and you could have seen through it.
Hmm, all I need is an artist, a manufacturer and a distributor and I could sell these to schoolkids...