At the ringcrafts that I attend (very irregularly ;-) ) once we are standing up then playtime is over and pity help anyone who lets their dogs play

:-D One of the 'judges' is very strict about it and makes us all feel like we are back in kindergarten :-)
If you are uncomfortable about it then you could try moving your dog away from the naughty ones, or having a quiet word with whosoever is in charge. They maybe don't realise just how bad it is.
At the end of the day you are teaching your dog how to behave in the showring, and playing isn't usually allowed. You never know when the judge is looking ;-)
Edited to correct punctuation.......