"Throws cold water on" is an idiom which means to discourage or dampen enthusiasm about something. Antonyms for this phrase would be "fires up," "sparks," "ignites," "encourages," "enthuses," or "inspires." These words are often used to describe inspirational or motivational speeches, events, or individuals that help build excitement and positivity. When we use antonyms to "throws cold water on," we are attempting to create a more positive and uplifting atmosphere. It is important to choose our words carefully, as they can have a tremendous impact on how others feel and respond to our messages and ideas.