The brutally honest one
“Remember to always be yourself. Unless you suck. Then pretend to be somebody else.” – Hearing the truth isn’t always easy, but sometimes it’s necessary, so this guy decided to be the bearer of unfortunate news.

This guy was simply trying to give his class mates some sound proof advice, and he’s not trying to sugar coat it. This is a funny quote, but not too optimistic, and gain, this probably isn’t how he’s going to remember his school years.
Short and to the point
“I am usually not one for speeches, so goodbye.” This girl quoting Ron Swanson from Parks and Recreation says it all without saying much. “Goodbye” is the best word to sum up high school.

She got the idea of the yearbook quote figured out, and I see a bright future for her. There’s not much to say after 6 years of high school except goodbye. And if you’re going to quote a T.V show, might as well make it Parks and Recreation.