Just thought that you might like the amusing story.

Last night I was enjoying a meal in the "Won Kei" a well-known cheap chinese restaurant in the Chinatown area of London. One of the chinese customers seemed to be high on something and after having loud conversations (in chinese) with a non-existant person, started singing very loudly. Now I'm not an expert in chinese song, but from the looks of the other oriental customers, neither was he. Several of the waiters tried to make him desist, but he just sang all the louder. In the end he turned to the restaurant and in very bad english, asked why he shouldn't sing. I couldn't resist telling him that it was illegal if the premises didn't have an entertainments license - he didn't sing anymore, much to everyone's satisfaction.

OK - I sure that it would have counted as spontaneous - and perhaps I've pissed off people as much by singing in some pubs - but I still found the incident amusing.