Classic joke at university was to sprinkle cress seeds on the carpet of someone's room and water it with a fine mist from a plant sprayer. In the morning the inhabitant would wake up to a neat lawn that had appeared overnight by magic.
Fell asleep in front of keyboard, woke up to "Can of Worms" screensaver (never seen it before), had a heck of a start, wondering what the sound was, and what all those things were crawling all over the screen???