"May I ask the gentleman," Roosevelt replied, quieting the crowd, "why he is a Democrat?"
"My grandfather was a Democrat," the man replied, "my father was a Democrat and I am a Democrat."
"My friend," Roosevelt interjected, moving in for the kill, "suppose your grandfather had been a jackass and your father was a jackass. What would you then be?"
Alas, Roosevelt was thwarted by the quick-witted heckler, who promptly replied: "A Republican!"