1 general:: see under THUMBS UP.
American Heritage Idioms
2 general:: Phrase(s): turn thumbs down (on someone or something) Fig. to reject someone or something; to grow to reject someone or something. • The boss turned thumbs down on Tom. They would have to find someone else. • The minute I saw it, I turned thumbs down.
McGrawhill's American Idioms And Phrasal Verbs