Back in the early 80’s when microwave popcorn was all the rage microwave ovens were still a little expensive and were not ubiquitous yet. Fortunately there were a few regional popping centers that picked up the slack. You would place your bag of unpopped corn into the pre-paid mailer and send it off to the nearest center. They were outfitted with large commercial ovens that could handle 4 bags simultaneously. Your freshly popped bag would be placed in a foil lined box and immediately shipped back to your location. If you timed it right the bag you sent out on Monday would get back to you just in time for the Friday night movie.
Canada! Come see me this weekend at the free Toronto Comics Art Festival!