If someone throws cold water on your plan, idea, suggestion or proposal, then he or she disagrees with it and also makes it impossible to continue. The idiom has a connotation of disappointment and annoyance, and it describes an unpleasant, negative event for anyone. - See more at: http://www.awesome-idioms.com/idiom-throw-cold-water-on.html#sthash.UzgTvMkA.dpuf