We had a go as postgrads back at our Uni (1981) and after a drinking session post a football match against our old hall at how many people in a phone box. It was outside one of our favourite pubs. Given half of our side were 1st and 2nd team rugby players, and the rest hockey or soccer players, we weren't small. However we did equal the then world record of 11, without breaking a window. The world record then became 12 and is now 14 (Germany - bl--dy midgets, I bet.)