You might innocently join a channel and find yourself quite lost in it. The people there might already know one another and might suddenly turn on you, which can seem very strange. Remember that chat is a very transient, here today, gone tomorrow experience. If you don't like what people are saying in a chat channel, just leave it and join another one on the same server, or quit the server altogether and find another one. Chatting is also very informal and relaxed.
People say what's on their mind.
Channels can move very fast when they're busy. If you see someone talking in a way that offends you, quit the channel. You don't have to give any reasons Equally, don't be offensive yourself. Using IRC should be like meeting real people - if you are nice to others, they will tend to respond in kind. If you are rude and arrogant, you can expect to be ignored.