That disguise is a dead giveaway! Choose something less obvious.
I don't take anything from the roomâ€”that's a dead giveaway.
A:: The bright orange color of pumpkin is a dead giveaway that pumpkin is loaded with the important antioxidant beta carotene.
Also the big hole in my head is a dead giveaway.
This is pretty much a dead giveaway that the address is not what it appears to be.
A dead giveaway is if you get an email "from" a financial institution where you don't even have an account.