Calling a young woman names on the campaign trail is always ill-advised, just as a general rule. Making up your own insults can show cleverness. But insults that come out of nowhere and make no sense show something else: cognitive problems.
The entire media should be screaming about Joe Biden's weird comment to a polite and rational question. But they are not. This and many other reasons explain why mainstream media outlets do not have the credibility of yore.