Syntax: GROUP target password
This command makes your nickname join the target nickname's  group. password is the password of the target nickname.
Joining a group will allow you to share your configuration, memos, and channel privileges with all the nicknames in the group, and much more!
  A group exists as long as it is useful. This means that even if a nick of the group is dropped, you won't lose the shared things described above, as long as there is at least one nick remaining in the group.
You can use this command even if you have not registered your nick yet. If your nick is already registered, you'll need to identify yourself before using this command. Type /msg NickServ HELP NickServ for more information. This last may be not possible on your IRC network.
It is recommended to use this command with a non-registered nick because it will be registered automatically when  using this command. You may use it with a registered nick (to  change your group) only if your network administrators allowed  it.
You can only be in one group at a time. Group merging is not possible.
Note: all the nicknames of a group have the same password.