in the words of Abraham Lincoln:
Be excellent to each other... and... PARTY ON, DUDES!
more specifically I'll paraphrase some examples from a german automotive corporation as they cover all the bases without being too wordy
- intimidation, harassment, trolling
- insulting, derogatory, harmful or prejudicial comments
- posting private information without permission
- political or personal attacks
- being nice, friendly, welcoming, inclusive, mindful and empathetic
- acting considerate, modest, respectful
- using polite and inclusive language
- criticize constructively and accept constructive criticism
- respect different points of view
- parse opinions and feedback objectively without prejudice
- it's the message that matters, not who said it
aaand that's how you say be nice in a way that fills half a floppy w