"Laddybuck" is slang, and slightly insulting. A "lad" is a boy, and a "buck" is a young horse... so, laddybuck is "a young boy with bad manners, like an untrained horse."
"I'd pull yourself together, laddybuck," Wilson said very quietly. (Ernest Hemingway "The Short Happy Life of Francis Macomber")
by Khnyka July 31, 2013