a yiii is the term used for the ‘bestest most awesome person in the world’

You could compliment someone by calling them a yiii.
person one: hey i think your really cool, your such a yiii!

person two: thanks! your a yiii too!
by anondjîck🔮 July 24, 2019
Meaning yes, but more enthusiastically.
Ex. Teacher, "Bobby, you have no homework tonight." Bobby, "Yiii!"
by Yiii December 3, 2013