drop like a stone

1. To fall, plunge, or collapse very quickly, suddenly, and heavily. I watched in dismay as my phone dropped like a stone down to the bottom of the lake. He seemed perfectly fine, but then all of a sudden he just dropped like a stone. The doctors say he suffered a massive heart attack and died almost instantly. Don't tell Mom, but I was carrying too many things this morning, and one of my textbooks dropped like a stone onto her prized tulips.

2. To decline very quickly and suddenly, as in value or standing. He had been on top for most of the tournament, but after two tough losses he dropped like a stone to sixth place. The US dollar has been dropping like a stone over the last few days as the economic crash continues causing havoc. The new smartphone was meant to revolutionize the industry, but it dropped like a stone after its commercial release.