I had a bright orange envelope I wanted to recycle, and I thought I'd try spattering some paint on it to cover some unwanted advertising. This is where you get some slightly watered-down paint on a brush and tap the brush perpendicularly against a stick or whatever. I had an old magazine open under the envelope to catch the "overspray," and I noticed the spattering looked nice on a dark area of the page, so I decided to do several whole pages like that. Above is one result. The spatters nicely cover the original art on the page while some of the original color shows through. I might use this for Christmas cards. Below, I see lots of little Space-fish swimming through the Milky Way.
This is very, very messy. I spread paper all over my desk and still got spatters everywhere; on me, on my clothes, on the wall. Here's the piece of 2x4 I played with the brush. I feel like the hippie version of Jackson Pollack.