Wiktionary
dittohead
n. 1 (context US slang pejorative English) One who agrees with an idea mindlessly, especially those who agree because they are supporter of the person who started the idea. 2 (context US slang English) Someone who is a fan of http://en.wikipedia.org/wiki/Rush%20Limbaugh's radio program. 3 (context US slang pejorative English) A person who agrees with Rush Limbaugh unquestioningly.
Usage examples of "dittohead".
This was a crowd even rougher than the Rush Limbaugh dittoheads terrorizing Tom Daschle in the fall of 2002.