1.A form of agreement.
2.A form of exictment.
3.As used in Friday after next.
"Yea boy,that's nice."
what someone says rappidly over and over again in a high pitched voice when they are having an orgasm or are getting sexually excited.
Some dude: "Oh crap don't get in there that's my!-"
Some other dude: "YEA BOY YEA BOY YEA BOY YEA!"