I cannot believe that it took me this long to find out you can do this...there are tons of recipes for it online. The butter flavoring in microwave popcorn is bad for the lungs, and all the fat and salt in it is bad for the heart, plus it is like 5 or 6 dollars a pound, but it's a bit of a hassle to pop it at home otherwise. UNTIL NOW.
Homemade Microwave Popcorn
1/4 to 1/2 cup of plain old popcorn
1 brown paper lunch sack
Optional - 1/2-1 tsp canola oil or butter, 1/4-1/2 tsp salt, or garlic salt, plus some black pepper if you like, or parmesan, or crumbled nori
Toss in the bag, fold over the top a couple of times, and microwave for 2 or 3 minutes, until there's only a pop every 2 seconds or so. Makes like 30 bags for a couple of bucks! And no popcorn lung
I thought it might burst into flame or something, but I've had 3 bags in the last 24 hours, and so far it is only delicious delicious corny popcorn goodness.