There's a subreddit called Redditgetsdrawn where people post (usually undrawable) pictures of themselves and people draw them. It's somewhat valuable for beginners but drawing webcam shots of half a person's face isn't much help. More interestingly, there's a knockoff called Redditgetsdrawnbadly.
Anyways, with the pressure of constantly trying to make the best art possible, always pushing to the limits, it's really fun to purposefully be bad and/or make people look terrible. It's great for the 'serious' artist who has an inner cartoonist with an 8-year old's sense of humor.
And I'm not affiliated with the creator of the subreddit in any way. I'm just trying to get the community going. It's a pretty new site.