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.
Tweet: Yo, governor after saying you want to protect our communities, why did you
vote to support that bill which makes it easier for
children to buy
guns? WE SEE YOU. #election