Locked With Key on Facebook

What it signals here

reaction meaning

Used in comments to indicate something is a sure thing or to affirm that a relationship or arrangement is solid and official.

comment use

Placed under couple photos to congratulate or validate the relationship, or under business posts to imply a deal is secured.

boomer interpretation

Likely interpreted literally as relating to home security, computer passwords, or keeping something safe and private.

group use

Used in private group chats to signal that group information is confidential or that membership is exclusive.

See it elsewhere