I'm not even remotely serious.
Sadly, I have this problem in real life. I deadpan everything (I grew up inspired by Daria), and often times it goes way over people's head. The worst part is, thinking back on it, I am always a little tickled by the fact that they thought I was serious. For some reason, I sometimes find it funnier when I'm the only one in on a joke; probably makes me some sort of jerk ^_^.