Who said "Dude, we're in third grade"?

This quote is attributed to Kenny McCormick.

Dude, we're in third grade - Kenny McCormick

"Dude, we're in third grade"

Kenny McCormick Humor

"Mmph mmph mrmph!"

"I'm not fat, I'm just big boned"

"This is so cool"

"You guys, seriously"

"Never underestimate the power of a good laugh."

"Laughter is the best medicine."

"A good laugh is the best medicine."

"Laughter is contagious and wonderful."