In case you ever get something like this: http://i.imgur.com/vyzPfNA.jpg
(It's too big for me to post!)
You can fix it and get back to your desktop with:
sudo chmod 1777 /tmp
That's how I was able to fix it!
That is all.
Felt the need to post this because I been messing with this for several years, and this is the first time I ever come into a problem like this. Weird, huh?