As part of my dedication to staying in Emacs, I feel that I should endeavour to keep it open all of the time. While I can normally manage this, my mind occasionally wanders and reflexes take over and I find myself unintentionally chording the exit sequence. First, let's use the describe-key help facility (C-h k) to discover what is bound to the exit sequence (C-h k C-x C-c):

C-x C-c runs the command save-buffers-kill-terminal (found in global-map), which is an interactive compiled Lisp function in ‘files.el’.

It is bound to C-x C-c, <menu-bar> <file> <exit-emacs>.

(save-buffers-kill-terminal &optional ARG)

Offer to save each buffer, then kill the current connection.
If the current frame has no client, kill Emacs itself.

We can unbind the key using global-unset-key: 

(global-unset-key (kbd "C-x C-c"))

Now when we chord C-x C-c we will receive a message in the minibuffer stating "C-x C-c is undefined". Now since my goal is only to prevent myself from unintentionally exiting Emacs, I should mention that I can still trigger the function that closes emacs (exit-emacs) by calling it directly with M-x save-buffers-kill-emacs. Let's look at the help for M-x, which is used to execute any command that is configured as being interactively callable:

(execute-extended-command PREFIXARG &optional COMMAND-NAME TYPED)

This function is for interactive use only; in Lisp code use ‘command-execute’ instead.

Read a command name, then read the arguments and call the command.
To pass a prefix argument to the command you are invoking, give a prefix argument to ‘execute-extended-command’.