This is a little off topic too, but I remember back in Gr. 9, our Jazz Band went on an trip for a few nights to Nanaimo for the Kiwanis Jazz Festival. Now I was not going to meetings at this time, but there were two JWs who were also on the trip (actually, pretty nice people). Well one of them had a mom who could only be described as a super JW. She made sure her son only stayed a day and when they were finished playing, she drove all the way to Nanaimo (which includes a ferry trip) to pick him up and take him home. He wasn't made fun of by other people like most JWs would expect, but everyone felt sorry for him.
Personally in assemblies that were non-holiday, I just didn't sing the national anthems (God Save the Queen at the start and O Canada at the end -- in the late 1990's). But in the holiday ones I just had to wait outside at the office, which was a throughly embarressing experience. Now that was elementary school. In Grade 8 @ Secondary, I was pseudo-JW, not doing holiday stuff especially for concerts, but by Gr. 9 I was doing all the holiday stuff and having fun doing it. Then in Gr. 10, I got to do all the Mayday Songs like Amo Amos, that chesnut song, the Coronation March by Meyerbeer, and the National Anthems.