I think mine just came to me one day in high school probably 10+ years ago. Random eureka moment I guess, if you could call it that. "de" + "caliber" doesn't make one bit of sense if you think about the actual meanings. I guess I liked it at the time because it had some seemingly insidious undertones.
Every since I moved to IL though, people have been asking me if I'm from Dekalb county.