“He grew up to be a fine waule fallow, like mony ane thatcomesoʹ the wrang side oʹ the blanket.”—Sir W. Scott: The Antiquary, chap. xxiv.
A wet blanket. A discouragement, a marplot. A person is a wet blanket who discourages a proposed scheme. “Treated with a wet blanket,” discouraged. “A wet blanket influence,” etc. A wet blanket is used to smother fire, or to prevent one escaping from a fire from being burnt.