"A sexy way of saying, "Yay". Or When Yay and Yup are Combined.
Girl: "Take off your clothes, we're having sex."
1.That asian kid that was so coo. Had a gay sister named susan tat was always on myspace.
2.The guy that lobed to no scope and pwnz.
someone: Hi YUY!
Yuy: Hi gay!!!! my sister is gay