To state the obvious, there is something about this drink that just works. The true classic doesn't include lime, but here in the U.S. we have made that an expected addition. Meant to be enjoyed on a 90 plus degree day when the humidity is just high enough to keep a permanent shvitz on.
2 oz. Gosling's Black Seal Rum
3 oz. Reed's Ginger Beer
.5 oz. fresh lime juice
Combine the ginger beer and lime juice in a tall glass over ice. Slowly top with the Gosling's and garnish with a lime wedge.
Obvious Note: While you don't need Gosling's or this drink the rum has gotta be, in the words of David Wondrich "dark and funky".