nodder
n.— «I thought it would be just the two of us and a hi-fi. But I ended up in a recording studio with about 20 nodders; a nodder is someone who gets paid to agree with the person paying him.» —“Cowell Regrets Not Being Honest About Murphy’s Pop Tunes” Contactmusic.com (United Kingdom) Jan. 15, 2007. (source: Double-Tongued Dictionary)
Further reading
When there’s no evening meal planned at home, what do you call that scramble to cobble together your own dinner? Some people apply acronyms like YOYO — “you’re on your own” — or CORN, for “Clean Out your Refrigerator...
You know that Yogi Berra quote about how Nobody ever comes here; it’s too crowded? Actually, the first person to use this was actress Suzanne Ridgeway, who appeared in several movies with The Three Stooges. A new book shows that many well...
One of P.G. Wodehouse’s Hollywood short stories features a Nodder. (He hopes to work his way up the career ladder to Yes-man.) The story probably dates from the 1930s. If it’s to the point, I can look it up.