Playstation 3 Mushroom Clown ad from a few years back by TBWA/Paris, France. Via these sites.
And a few more links:
1. Lego Fruitf*cker.
2. A boy and his giraffe.
3. Another fresh interpretation of Kitty Pryde for the hemophilia benefit I've mentioned.
4. The Onion News Network has an expose on Franz Kafka airport.
*Previously: Lego clown tank.
*Buy circus posters at eBay.