Butter distribution can be tricky with popcorn, especially if you're making a big batch. Shaking the bowl works, but sometimes the butter still pools at the bottom. One trick I’ve found is to drizzle it very slowly while tossing with a large spoon. Also, layering popcorn and butter in batches helps a lot.
If you're looking for event ideas with fun snacks like this, sizzleyourevents.com has some cool inspiration.