Flags made up from geo shapes. The blue areas are lakes, yellow is beach. If you go into Google Map Maker you can do stuff like this, but that it got past some type of approval from a mod seems like a real cock up.

This deep-link shows the "East" object, which is a lake: http://goo.gl/zRoZqS

edit: Upon further digging, there is either a group of people or some automation involved, as they've not only submitted these new features, but managed to gather enough upvotes that they seem to have snuck through the system as I can't imagine this getting by any standard human review.

I've reported the shapes as spam, but when it's this easy to get something silly through in the middle of San Francisco, you have to wonder what else has been changed over the years.

edit2: Do yourself a favor and check out how many of this user's edits have been approved & published: http://www.google.com/mapmaker?gw=66&ptab=1&uid=209018779364...