What I mean by this is those who condemn adults having fun without children. For example, condemning a group of adults making a big deal out of Christmas when there are no kids involved. Or condemning adults enjoying theme parks with no teenagers in tow. Or condemning adults enjoying Disneyland with no kids.
I am not personally into all of the activities I have named, but you don't need kids with you to enjoy yourself. If adults enjoy these kind of things, then let them enjoy them and don't look down your nose at them.