In a small bowl, melt the butter. Add the Sriracha and stir to combine.
Place the popcorn in a large bowl. Slowly drizzle the butter mixture over the popcorn, stirring as you go. Add salt to taste and stir some more.
Sprinkle the finely shredded cheddar over the popcorn and gently stir it in. Serve immediately.
Notes
You can use any kind of hot sauce you want, it doesn't have to be Sriracha. That's just my favorite. Also if the cheddar cheese weirds you out, you can skip it. It's good without it.Source: adapted from The Curvy Carrot