Caiparinha
Muddle half a lime (or more) in the bottom of a tall glass
add ice cubes to the top
add a tablespoon of sugar (coarse brown, or refined, your call)
top it off with cachaca
Brazillian drink, cachaca is kind of hard to find, its distilled sugarcane but not rum
Tricky part is getting the lime and sugar ratio right, it can depend on the ripeness of the lime.
But if you get it right... wow so good, goes down like lemonade on a hot day. But you are essentially drinking straight rocket fuel, so it can knock you on your ass.