I got my first bow tie in college by completing a dare. A friend of my dared me to wear clothes he hand-picked out of the "missionary barrel": a polyester green shirt and plaid pants. I had to wear them through lunch; my reward was a Ralph Lauren/Polo bow tie. Since then, I've slowly acquired a number of bow ties and like to wear them on most occasions.
In fact, I typically wear a bow tie the first day of class (have since college). I don't, however, wear a bow tie when I'm preaching: I'm fearful of being too self-conscious and having people wondered, "Did he tie that himself or is that a clip-on?" instead of listening to the sermon.