I’m a big fan of advertisement-hacking, and I think quite a lot of people here will get a kick out of this one, so even though it was linked in the linkspam I’m putting it up here:
Public transit ad depicting a brain: note pointing to one side says "Can you solve one of our puzzles" and the note pointing to the other side reads "can you explain it to your mom?". Text below reads "We're hiring hackers with people skills". Someone has added a post-it note to the advertisement which reads "My mom has a PhD in math"
Edit: If you’re crediting this photo, it was put on twitpic by jessiebennett. Some people are giving GeekFeminism.org all the credit which doesn’t really seem fair!
Edit 2: Note the appology from ITA in the comments.