So what is the reason for being banned from chat?
People can be banned from chat for one of two reasons:
one or more of their messages is flagged as rude or abusive and the flag is validated by other users;
they are temporarily suspended by a moderator, usually for inappropriate conduct.
Do I have to be nice?
Yes. We expect community members to treat each other with respect … even when they don't deserve it.
This site is collectively moderated by the community through participatory flagging. If your chat messages are repeatedly being flagged by your peers you might find yourself muted, banned, or – in extreme cases – your The Stack Exchange Network reputation may be negatively affected.
If you see an inappropriate, spam, or offensive chat message, please use the hover menu at the far right of each chat message to flag it. This will draw it to the attention of the community moderators.
More information on the technical workings of chat flags may be found in this main meta post.
In your case, you first posted two messages which were flagged and earned you short suspensions:
@Aegon, retrads are retards, what can I say
I take the good with the bad, and shit on the bad
This was in the context of you persistently posting comments accusing people of being "retards" for downvoting your question, and then arriving in chat to defend your actions and claim that you were just "calling a retard a retard". In view of this, your comments were flagged, the flags were validated, and you got a short automated suspension.
Upon your return from this suspension, you said:
OK, I will use spastic from now on
This comment was also flagged and deleted, and then a moderator (not me, although I fully support their decision) gave you a 2-hour suspension from chat. You were showing no sign of learning from your mistakes, despite many people in chat trying to educate you in both the Be Nice policy and basic courtesy. At this point, your insistence on posting insults had gone too far.