I have heard from doctors that the main source of injuries for children on trampolines is having more than one child at a time on. I know that the guidelines you get with a trampoline strictly forbid this too.
We don't have a trampoline ourselves, but a couple of times now we have been visiting friends who do. They urged on child after child. I felt really mean saying that mine would be the only ones not allowed to do "group bouncing". Eventually I caved in - but felt uncomfortable, and now it's niggling at me.
Is it really common to ignore the basic safety rules in this way?