Most often the Disney World Cast Member is dressed like the janitorial crew, but instead they are armed with a broom and a bucket of water.  These talented artists then create Disney Characters, usually Mickey Mouse, in water on the sidewalk of street with little to no fanfare.

The fragile, temporary nature of painting with water is part of the charm.  This is truly about sharing a magical moment, because soon the water will dry and all evidence of this work of art with disappear.  The Epcot Cast Member pictured below was in the World Showcase near the Canada Pavilion and was quietly creating Mickey Mouse.  At the end he asked the children nearby if they would like to help color in Mickey Mouse's eyes and nose.  This added touch was very nice.

Here is a video of the Epcot Cast Member finishing the Mickey Mouse Water Painting.  Once people realize what is going on, they stop to watch.