A sign that I've acclamated

Today as I was boarding the tube to go to the CAPA center, a group of American high school students boarded the carriage. You would have thought they were parachuting off a crashing plane. A leader of the group kept yelling, "Everyone can fit on the train, keep moving!" It's British tube protocol to stay silent, or at most whisper, when riding. These kids were extremely loud and chatty, and we were afraid we wouldn't be able to get off at our stop. We felt embarrassed they were Americans.