One of the easiest and cleanest ways to create groovy swirls on paper is to use shaving cream.
It's clean, smells good, and washes right up!
Find a tray and make little shave cream piles.
Drip a little watercolor paint or food color on it.
Use a toothpick, fork, chopstick or your finger to swirl it around.
Swirl some more until it looks awesome to you.
Press a piece of cardstock onto the colored shave cream. Wipe off.
An incredible design will remain.