These were some sketches I did a while ago. Of me, in the mirror. My goal was to draw as fast as possible, but I really loved how they came out! They're not really like the way I would draw at all. I think they've got a real Quentin Blake-ish feel to them.
I like setting myself little drawing challenges, creating a sketch in a couple of seconds, blind drawing, left-handed drawing, etc, you can produce some really interesting stuff.
It's allowing yourself to let go of the control, allowing yourself to be a bit looser, to roughen up.