https://marco.org/2008/03/24/nath-look-at-the-sky-pick-a-random-object-hold
nath:
Look at the sky, pick a random object, hold it in front of the clouds and take a picture. ‘Fun with Clouds’ is the unofficial name for this series of photographs that makes you to use your imagination in order to create cool illusion effects with the different shapes of clouds (more examples here).