In comics and other pop culture, I have since a very young age heard the word tinhorn and kinda-sorts assumed it meant about the same as "greenhorn," an inexperienced or naive person. But "tinhorn" actually means a cheap person, or a scoundrel, especially one who gambles for low stakes.
The Online Etymology dictionary says tinhorn comes from the tin cups the gamblers used to rattle dice. Which of course gives rise to the question, what's the horn part? Well, that's from the horn of an animal, but as a verb, as in to horn in on something. So a tinhorn is a gambler, shaking a tin cup, horning in on game but not playing for big money, so kind of bothering everyone. World Wide Words has an excellent summary of the derivation.
