Placebo is the opening word of the antiphon of vespers in the Office of the Dead, used as a name for the service as a whole. The full sentence, from the Vulgate, is  I will please the Lord in the land of the living, from Psalm 116:9. To sing placebo at a funeral came to mean to falsely claim a connection to the deceased to get a share of the funeral meal, and hence a flatterer, and so a deceptive act to please.