No, not a mere crass joke.

Trump's style is to try saying different nasty things in order to see which sticks and makes his opponent to lose balance.

Trump did this on Ted Cruz, insinuating threats to his family. It was something that affected Cruz and contributed to him having a bad campaign. Cruz even mentioned this recently when he refused to endorse Trump.

Trump and his media team repeat adjectives when refering to opponents, like "crooked hillary". Cruz was the "zodiac killer".