What does “get down with the kids” or “be down with the kids” mean? [duplicate]
Get down with the kids normally mean speaking the children's language and be less like a adult with the kids.
But it can also mean enjoying yourself without restraint with the kids, as suggested by CED:
get down
informal (mainly US) to enjoy oneself uninhibitedly, esp by dancing
(with friends in a social setting) get down and party!