An older man that I know said that golf used to mean "gentlemen only, ladies forbidden". Does anyone know if that is true or just a joke?

That's an urban legend.
Is Golf an Acronym for Gentleman Only, Ladies Forbidden? (http://golf.about.com/cs/historyofgolf/a/hist_golfword.htm)

This might help, certainly a good read: snopes.com: Golf: Gentlemen Only, Ladies Forbidden? (http://www.snopes.com/language/acronyms/golf.asp)