Things not to do in Tiananmen Square

Here's a sign posted on entry to the shopping district just south of Tiananmen Square. I can't figure out if it is real or a joke of some sort. I can also understand why some of these things would be ill-advised in a public space, but I say that if you can figure out a way to operate a standard surf board hundreds of miles from the ocean, on concrete and with a few thousand people in the way... hell, you should be allowed.