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Stands for Beastly Yeast Infection. Used, obviously, if someone has a very bad yeast infection or someone thinks they have a yeast infection.
Shanon: Ugh, i think i have a yeast infection
Kristin: Yea, a BYI, beastly yeast infection!
by J. Chan October 14, 2006

Words related to BYI

b beast beastly infection pee yeast