Lime is a four letter word.
When I was a child, my family drove down to the Florida Keys, where I experienced my first taste of Key Lime Pie. I was captivated by the dessert, and the many ways that it was presented there. But what I loved the most was the sharp taste that the limes brought - at a time when I thought desserts had to be sweet, it was my first introduction to the many layers of flavor that foods can present at the same time.
A Key Lime is different than the limes that most people are familiar with. They're typically more round and more yellow than most limes, and their flavor is sharper than a typical lime. Most surprising to me at the time, however, was learning that most Key Limes were imported from California, a blight having wiped most of the native limes out some years before, apparently.
That isn't to say I don't like other limes as well - my favorite drink is cranberry juice with a slice of lime.