one of the members of this group (the Insane Clown Posse) goes by the name of Shaggy 2 Dope. In saying it ain't no thang, he's saying everything is fine.
he is upset that the woman he slept with did not tell him about the sexually transmitted disease she had before they had intercourse, because now he has "bugz on his nugz" (a sexually transmitted disease on his genitals)