Charlie Boy

What is the meaning of the euphemism: "Charlie boy?"
In a 1907 University of Nebraska yearbook, it was said of a graduating senior, "Roy Dwyer. He might be called a 'Charley Boy' or 'Mother's Pet,' if we did not know him." In the 1960s it was said of Roy, since deceases, that he had effeminate mannerisms. I am curious to learn whether the term "Charlie Boy" had particular meaning in 1907 culture and language. Can anyone help me with this? I'm wide open to insights to my grandfather.