If you've ever read the XKCD webcomic, i'm guessing you've red the "My hobby" issues.
Here are some examples:
http://xkcd.com/437/
http://xkcd.com/259/
http://xkcd.com/331/

Now, make your own! I'll start.

My Hobby: Going out on ridiculously cold days and watching my spit go "clunk".