Stovetop: Place oil in a tall pot over medium heat and add the popcorn kernels. Cover the pot with the lid, leaving it slightly ajar. The kernels will start popping after a bit. Keep the pot over the heat until the popping slows down. When you check inside the pot, the kernels should be popped. Turn off the heat.
Line a 13x18 baking sheet with wax paper. Pour the popcorn onto the baking sheet and carefully remove and discard any unpopped kernels with a spoon. (The kernels will be hot.) Sprinkle the popcorn with the salt. Using clean hands, mix the salt and popcorn together. Spread the popcorn out evenly.
Place a heaping half cup of semi-sweet chocolate chips in a microwave-safe bowl, covered with a piece of wax paper. Heat for 30 seconds, then stir. Heat it for another 30 seconds and stir. You may need to heat it for another 20 seconds or so to finish melting it, depending on your microwave. Stir your chocolate until it is smooth. Dip a fork into the chocolate and drizzle it all over the popcorn. If you twirl the fork a bit, you will get thin ribbons.
Melt a heaping half cup of white chocolate chips in the microwave, using a different bowl, but following the same process as before, stirring it after 30 seconds, etc. Dip a clean fork into the melted white chocolate and drizzle it over the popcorn. Let the chocolate dry. (It took at least 30 minutes for mine to dry using the chips, but candy melts dry faster.)
When the chocolate is dry, it's time to flip the popcorn over and drizzle chocolate on the other side. (I place a clean sheet pan over the popcorn, and invert the popcorn onto the clean pan.)
In the microwave, melt another heaping half cup of semi-sweet chocolate in your chocolate bowl from before. Use your chocolate fork to drizzle on the melted chocolate over the popcorn.
Melt another heaping half cup of white chocolate chips in the microwave, using your white chocolate bowl from before. Dip your white chocolate fork in and drizzle the white chocolate all over the popcorn. Let the popcorn dry before packing it into bags. (You can refrigerate it for a bit to speed up the process.)
Dorm Room Version: Pop one bag of microwave popcorn. In a microwavable bowl, place a heaping half cup of semi-sweet chocolate chips and cover it with wax paper or a paper towel. Heat for 30 seconds, then stir. Heat for another 30 seconds, and stir. You may need to heat it for another 20 seconds to completely melt the chocolate, depending on your microwave. Stir the chocolate until it is smooth.
Place the popcorn in a large bowl, if you have one, or portion it out onto small plates or bowls. Carefully remove and discard any unpopped kernels with a spoon. (The kernels might still be hot.) Dip a fork into the chocolate and drizzle it all over the popcorn.
Melt a heaping half cup of white chocolate chips in a clean, microwaveable bowl, using the same process as before. Use a clean fork to drizzle the white chocolate over your popcorn. You can try waiting until it dries to eat it, but I'm sure you will go to town before it dries!
You can repeat the process with your second bag of microwave popcorn and more melted chocolate.
If you are using microwave popcorn bags, you won't need to add salt or oil, since it will be seasoned already.