long drink of water
1. A tall, typically slender person. Who's that long drink of water who just walked into the bar? You're a long drink of water, aren't you? What are you, six-foot-five?
2. A rather boring, plain, or uninteresting person. Sarah's new boyfriend sure is a long drink of water, huh? He barely said a word all night.
long drink of water
A very tall person. “Look at that basketball player—what a long drink of water!” The image is the distance that water would travel down the throat of someone of great height.