Love locks I believe. A couple writes their names on the lock, attach it to a bridge or structure and then toss the key as a symbol that their love is forever.

The tempation, just putting your hands against them and start running, the Sounds they could make…

First result on google say it’s valentine’s day gimmick from 2015:

https://lovelockdiaries.wordpress.com/2017/05/22/wishing-bells-in-singapore/