Way back in the pre-Internet days, magazines often had little classified ads sections in the back. There was nearly always a couple of businesses that almost said they would send you pornography, usually for scientific and educational purposes; an offer to sell you a weather balloon or information on ham radio clubs or telescope kits; and at least one ad like this:

Make money at home stuffing envelopes! Send SASE and enclose $2.50 for our guide on how you can make money in your spare time!

And if you were foolish enough to send them the money and a SASE -- a self-addressed stamped envelope, the equivalent of an HTTP GET -- you would get a sheet of instructions, which began: "Take out an ad in a magazine telling people to send you a SASE and money. Make copies of this sheet and stuff them in the SASEs..."