Maturity and a Donkeys Tail

My sons 17th Birthday today,a mixed sex group of his friends are coming round and my wife felt we should put this up in case the conversation started to wane.
My daughter of 21 pointed this out as a big mistake,but we are going for it anyway.
So if you are happy to take part for a laugh you are either a child or mature.
If not happy,probably heading towards maturity or senility but not quite there.
Well that's my take on the donkey tail guage!