On's Geeks community, Joel said:

You're right. Geekiness is the state of wanting to know and understand everything. True Geeks can geek on any topic, after very little preparation.

Example: My degree is Chemistry, I work in computers, and I do theater tech/SF conventions/other cons/etc. on the side. My GF is a mechanincal engineer (and just as much a geek). I make her crazy sometimes because just talking about what she does at work I'll pick up enough about stuff (that she has a degree in and I don't) to make informed suggestions as to how to fix problems they're having.

This goes hand-in-hand with the state of "Being an Engineer". PEs will make you believe that it involves much training, experience, and certification. I claim that it is a state of mind, encompassing a certain level of geekiness, and a whole lot of logical problems solving.