The Monkey Fluids blog (link at the bottom so you don't click through without warning), involves a guy putting new captions to illustrations from children's annuals and storybooks. As might be expected, many captions are obscene, others just bizarre, but almost all are hilarious. Better still is the comments section, where you can come up with your own caption, and astound the world at your wittiness, knowledge of pop culture and lack of taste.
As might be expected I occasionally post comments there. It's here.
(My favourite? I'm glad you asked.)