Have you taken those 'spinning ballerina' personality tests?

[Telarus]

You totally got LULZ-O-FIVE'd.

http://www.theregister.co.uk/2010/12/22/silhouette_illusion/

When I first encountered this, I did what I always do with optical illusions. I try for a 'no-mind' state, and see if I can get the illusion to 'flip' (see the 'young woman/old woman' illusion). This one was pretty easy to do as well, took a few 2-3 minute practice sessions. It's good to know exactly which part of my brain I had setup a feed-back loop for, the perception of looking 'down' or 'up' at something. Crazy.