Hard to say no one does anything when you see the massive riots and protests that have occurred recently. And are so many black people killed by police? They don't seem to be killed more than other groups. So maybe police killings in general are a problem, but they don't seem specifically directed at black people.

lolcow - scheme or meme dreamed up by internet nerds that has the potential to cause humorous results (see: 4chan posting fake apple ads online saying your phone could be charged by putting it in the microwave, 4chan saying you could drill out the bottom corner of your iPhone to uncover the "secret" headphone jack, etc.)

This is a meme completely generated by online pranksters, but some/many left leaning activist types take it EXTREMELY seriously. For examples [1] [2] [3]. There are tons of things like this (I mentioned hawaiian shirts being one of the latest); they're mostly generated as pranks on imageboards, and as far as I can tell, they're designed to discredit humorless leftists, rather than actually transmit high frequency right wing brainwashing messages. Imagine being a normal person who makes the OK sign, or wonders out loud why it isn't OK to be white and is condemned as an evil nazi by .... "activists" for the full effect. I mean, the OK sign has been used for assent for ... what? 2500 years?

I'll let you figure out lolcow on your own.

[1] https://www.adl.org/blog/how-the-ok-symbol-became-a-popular-...

[2] https://www.splcenter.org/hatewatch/2018/09/18/ok-sign-white...

[3] https://www.dailykos.com/stories/2017/2/21/1636419/-Yes-Trum...

As for lolcow, you'll be more entertained if you google it than if anyone explains it to you.