Officially the Combine Civil Authority, more well known among the civil populace as the Metropolice or Civil Protection, are the law-enforcing, citizen-beating, rebel-executing police force of the HL2 games and it's Garry's Mod Roleplay Gamemodes.
Bob Good says "Man, I just really can't stand all the oppression, you know?"
Drake Rodarthe says "Shh! I wouldn't say that too loud, you're not gonna want the CCA to hear that. They're gonna beat you to a pulp."