Members any authoritarian figure, including government people, police and corporate management - possibly in some cases only including those on the front lines of population control (police, the media, your boss, your spouse, your parents, teachers, security guards, parking attendants, etc.).
Anyone which tries to control your thoughts, deeds, how you choose to communicate or what you choose to communicate about.
Possibly coined by the swedish hiphop group "Loop Troop".
"Cuss the downpresser men from the top of my lungs, 'til they start making sense and be dropping their guns" - Big In Japan, Loop Troop.
The downpressers on the east side of town beat up a little kid the other day for drawing an anarchy symbol at a train station. Their getting off scot-free, of course. Meanwhile the news is talking about dogs stuck in wells and how great the budget is going to be.