Fun. Commenting your code.
I was taught that documenting the code is almost as important as a writing it.
On this site you find some hilarious comments: http://stackoverflow.com/questions/184618/what-is-the-best-comment-in-source-code-you-have-ever-encountered
Like this one:
//When I wrote this, only God and I understood what I was doing //Now, God only knows
// should never happen }