How it’s served
Up
A drink served up has been shaken or stirred with ice, then strained into a stemmed glass with no ice in it.
In practice
A Martini or a Daiquiri is usually served up, in a coupe or cocktail glass. Chill the glass first, since there's no ice to keep the drink cold. "Straight up" means the same thing to most bartenders, though some use it for neat.
Drinks to try it with
Up, in short
What does up mean?
A drink served up has been shaken or stirred with ice, then strained into a stemmed glass with no ice in it.