This is a pun on 'court jester' which was a fool or joker was a member of the household of a nobleman or a monarch employed to entertain guests during the medieval and Renaissance eras, but 'gesture' is used in it's place because it sounds similar and because 'gestures' is a form of non-verbal communication or non-vocal communication in which visible bodily actions communicate particular messages, in this case shrugging 
When the King asked the fool for a joke the fool just shrugged . He was the court gesture .