Definition from Wiktionary, the free dictionary
dittohead (plural dittoheads)
- (US, slang, pejorative) One who mindlessly agrees with an idea, especially those who agree because they are supporters of the person who started the idea.
- (in particular, US, slang, pejorative) A devotee of Rush Limbaugh or his radio program.
- The Seattle Times. "On a mission to save America's natural majesty". Pg. H23. October 1, 2004.