In "homesick," why does ian forbes say, "you'll sing tomorrow…or you'll be sorry"?

autobiography of an ex-colored man is told from the first-person point of view of an unnamed male narrator. he starts his tale by stating that he is going to reveal the great secret of his life. he first takes the reader to his childhood in georgia where he was raised by a single mother. he was dissapointed in his own color.

ok what is this for my man