Advice of the day:
When it comes to individual words themselves, the worst thing you could say are racial slurs. But when it comes to phrases, the most offensive things you could say are death threats (especially terroristic threats). We must avoid the extremes at all costs.
But if you want to be a good human being, you shouldn’t even say bad words or use rude language (including “stupid” and “shut up”). As part of being respectful, you should talk more kindly and don’t be mean verbally.