Recursion
From CodeStuff
This program draws a thing by drawing five lines. Across-Up-Across-Down-Across. It's like a horizontal line with a kink in the middle.
What would happen if we replaced the three horizontal lines in drawThing with a horizontal line with a kink by using drawThing to draw itself.
instead of drawLine(x,y,x+size,y) do drawThing(x,y,size/3);