last photo in the set referenced in your link shows numerous non-humorous protest signs and there's also anti-G20 sign among CMU guys. but my guess would be th

last photo in the set referenced in your link shows numerous non-humorous protest signs and there's also anti-G20 sign among CMU guys. but my guess would be that CMU guys and gals were just having fun. you can't really take this stuff seriously, G20 leaders probably weren't even in the line of sight with protesters at any time!