DS who is 6 has been invited to play at a school friends house. His parents are nice and friendly but have a much more casual approach to childcare than me. Last time he went to the house I discovered that he was playing on a trampoline having a wrestling match without a net around the trampoline. I have a real thing about safely on trampolines and this is really worrying me. I was caught off guard with the invitation and agreed to an after school play but I am worried. What would you do? I think I will offend the parents if I say anything.