I need to join to 21 channels, but my server only allows 20. What can I do?

Well, first, consider leaving some of the other channels that you are in. After all, how many channels can you really hold a conversation in at one time?

If you're sure you need all those channels, though, you'll have to reconnect to another server, one that allows more channels.
A list of all the servers on NationCHAT can be found at our servers list.