I enjoy browsing A Dictionary of Slang, written in the early 20th century by Farmer and Henley. I learned earlier that it was Henley's little daughter Margaret who influenced JM Barrie, a friend of her father's, in the choice of the then unusual name Wendy for the heroine of Peter Pan.
Reduplication is a feature of baby-talk (eg choo-choo, drinkie-winkie etc) and young Margaret, who had difficulty saying r, would call Barrie her fwendy-wendy instead of 'friend'.
Slang was just one of the interests of William Ernest Henley. He is best-known for his poem Invictus, which contains the well-known lines
I am the master of my fate,
I am the captain of my soul.
Incidentally, Henley himself influenced the creation of a great fictional character, just like his daughter did. He was friendly with RL Stevenson and Stevenson's character Long John Silver is said to be modelled on Henley (he had a leg amputated while a boy).