Back in October, I decided to take a look at the phrase "ACAB" written all over the city. Through a Google search, I determined it to mean "All Cops Are Bastards." This may not be entirely true.
Most people online seem to define it as "All Cops Are Bad." This could be a recent change, though.
I remember when I was part of marches for Mumia Abu-Jamal, there was a popular chant of "No justice! No peace! Free Mumia! Fuck the police!"
It wasn't long before it was edited to "No justice! No peace! Free Mumia from the police!"
Although perhaps less popular than the original, the latter version was safer and less off-putting.