Who said "Mmmmph! (That's the most honest thing I've ever said!)"?

This quote is attributed to Kenny McCormick.

Mmmmph! (That's the most honest thing I've ever said!) - Kenny McCormick

"Mmmmph! (That's the most honest thing I've ever said!)"

Kenny McCormick Truth

"Mmph mmph mrmph!"

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

"Dude, we're in third grade"

"This is so cool"

"Lucy, you got some 'splainin' to do!"

"You must always be honest with the people you love."

"Truth always comes out in the end."

"Honesty is always the best policy."