giveaway

He said he'd given up smoking, but the empty packs in the bin were a dead giveaway (= clearly showed the secret truth).

他说他已经戒烟了，但是垃圾桶里的空烟盒让他彻底露了马脚。

The furniture shop's offering three-piece suites at giveaway prices.

家具店正以极低廉的价格出售一组三件套家具。