During Aang's final days Appa refused to leave the little grass patch outside his window, looking through the window to make sure Aang was still there. One of Aang's final requests was to be taken to the window so Appa could lick his hand and hug the curly fur one last time.
Days later, all the way in the middle of the swamp, tapping into the spirit vines, Toph could feel both of their hearts stop at once.
With tears streaming down her face she suddenly felt a fresh breeze blow, and whispered to herself: "Yip yip, twinkle toes..."