As a kid I can remember seeing ads like this in the back of comic books and other publications aimed at adolescents. The gas is, you send away for some sort of sales kit, most likely a catalog and some motivational text, and then you could sell greeting cards and who knows what else to all your neighbors and extended family in hopes of earning enough credit to get some free stuff from the advert. It was your job to take the orders, collect the money, send it to the company and then deliver everything when they mailed it to you. This scheme for using a child labor farm sourced from comic books has been around for a long time, probably dating back to the 40’s with Grit, which amazingly, is still a thing. The practice of bribing kids with the potential to earn prizes probably had it’s heyday during the 60’s and 70’s. Here are 2 examples from the late 80’s and early 90’s in which you can earn a Nash or Variflex skateboard.