Homemade strawberry mojitos with actual strawberries. Not the manliest of drinks, but by all that is holy in the world there's little to beat it on a warm day.
I'm also partial to tequila - as long as it's not cheap tequila. Which unfortunately, outside of North & South America seems to be all that they have. The sheer number of foreigners I've met who say they hate tequila only to say that all they've had is Jose Cuervo makes me very sad.
And of course, a good quality beer that's nice and cold is always great. Whereas the mojitos are great on a warm day, on a warm night a cold beer is much more preferable.