a dead giveaway

a dead giveaway

Something that is an obvious clue about something else. Your shoes are totally sticking out of the blankets! That's a dead giveaway that you're planning on sneaking out as soon as mom says good night to us. The homemade card was a dead giveaway that they had forgotten to buy us a gift.
See also: dead, giveaway

dead giveaway

something that reveals a fact or an intention completely. The car in the driveway was a dead giveaway that someone was at home.
See also: dead, giveaway