(boys who attended yeeyee university) unreliable, tend to dip, statistically likely to leave/cheat/join military, drink 24 packs of beer all by themselves, can be associated tightly with the phrase "hold my beer" followed by performing a dangerous act (typically involving a tractor or four wheeler)
He is such a yee boi.
God, I love me some yee bois.
My town is full of yee bois.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi