Green’s Dictionary of Slang

(US teen) a gullible, conventional person, esp. one who permits hearsay to ‘pull their strings’ in matters of current taste.

1982–2004		G. Sculatti Catalog of Cool 🌐 puppethead (noun): Square person, esp. one who lets others pull his or her taste strings. (A typical puppethead remark: ‘Wow, I just paid forty bucks for tickets to see Devo. I’ve never heard them, but they’re supposed to be rilly neat.’).
1995		H. Stern Miss America 389: Any human being who wasn’t a trained puppethead would have hung up by now.
2003		MillionthMonkey posting at Calpundit.com 1 Oct. 🌐 Nobody here is dumb enough to think that Bush is anything more than a puppethead, smiling for the cameras and mispronouncing words in a charming fashion while the country is gangbanged by his friends.