I've taken this approach with humor as well. I'll intentionally start out sounding incredibly serious, then switch gears out of nowhere. That's usually a good way to get an honest laugh out of people because it catches people off guard. Taking this approach with serious writing helps lure people into the story and then again catches people off guard.

The Lawnmower Man. It's been so long since I saw that one, I could probably watch it again for the first time because I have no idea what happens.