Can you make popcorn in a pressure cooker?
I never tried it, but I don't think it is a good idea. 

The point of popcorn popping is that you cook the inside of the kernel within its hard shell until the internal pressure increases so much that it breaks the shell, releasing the starchy liquid inside as a foam. You need a pressure gradient, with higher pressure inside the kernel than on the outside. So, introducing high pressure outside the kernel is counterproductive. It will certainly result in more duds. I don't know if some kernels will be able to pop, but if yes, I expect them to take longer to pop, and create a denser foam, not light and airy popcorn. So, while I guess you could experiment with it if you don't have anything better to do, theory predicts that the experiment outcome won't be good. 

Why did you want to try it at all? Popcorn doesn't take long to pop.