When someone is being called out (usually on twitter) for not doing the right thing. Such as having the power to
stop something
bad happening but either failed to try and prevent it or worse, is found to have contributed toward it and
maybe lied about it or tried to cover it up.
The implication is that the person should be ashamed of their actions (or lack of) and that it has been noted so that at some point in the future they will
get their comeuppance.
It is essentially a thinly vieled threat that revenge will come, maybe not today, maybe not tomorrow, but one
day. Often written in all caps.