To clarify, I'm not asking how to make popcorn that tastes like movie theater popcorn (which typically comes from a popper), I want to know how to make the bad pre-popped popcorn that small theaters sometimes sell.
It's hard to describe the flavor, but it was almost this hint-of-mustard salty taste with semi-stale, but large and uncannily round kernels. The closest I've found (and it is close) is the plain popcorn that comes in those tins. My guess is that there's a preservative used that's imparting a taste.
Any ideas?