[giveaway] or [dead giveaway] {n.}
(stress on "give")
1. An open secret.
* /By mid-afternoon, it was a dead giveaway who the new boss would be./
2. A forced or sacrifice sale at which items are sold for much less than their market value.
* /The Simpson's garage sale was actually a big giveaway./
3. A gift; something one doesn't have to pay for.
* /The tickets to the concert were a giveaway./