Recently, at work, I used a little joke in code. It wasn't even in code, it was a log message, that was saying something like "Miserable failure!
The issue here is not this message itself, but the fact that it is prohibited to have this kind of fun at work, so it is implied that work is no fun. I even think that the most frank responce from my boss would be something like "I have no fun sitting here 9 hours a day so there is no way I'll allow you do it!"
This is what I like about FOSS: it is all about fun. It is fun to code, it is fun to use. All programming languages that dominate in FOSS world were created to have fun. Java is no fun, I don't like it, while Perl... yeah, Perl *is* funny