Sometimes when I get bored, I doodle. In the event that I cannot come up with anything to doodle, I play a game that I like to call, "Scribbles".
What I do to play this game is start out by drawing a bunch of random squiggly lines. Once I have a decent amount of scribbles, I look at each scribble and draw a character or object based on what I imagine the scribble being. As you'll see by some of the comparisons, the drawings don't always look exactly like the scribbles.
Above is a sample of some of my scribbles.
(Click for full size)