That happened to me on the double decker bus. I was sitting on the top floor, reading my book, and there was another bus coming toward us. I was looking at the bus, and these three kids in the front seats on the top floor (boys around 14 or something) poked each other like "hey.. dare ya.. let's do it.." and they all stood up and started to unzip their pants. I thought it was disgusting and TOTALLY distasteful. I didn't laugh.. I rolled my eyes and went to reading again, and once they didn't have an audience it wasn't fun anymore. Everyone else on the bus with me thought the same thing - not funny; totally rude.