I saw it in a graphic from Bookworm Room, The Scary Leftists Edition. The image didn’t (doesn’t) matter, because of the small eureka moment I had:
Guy 1: So, you’re saying if I am a socialist and I demand free health care, education and housing, and only law enforcers have guns, I should consider going to prison?
Guy 2: Well, of course, Prison is a much better alternative to socialism: they don’t run out of food.
It seems… yeah, yeah, I did slightly rewrite those sentences… it seems to me that the similarity between those two things, prison and a socialist society, is so obvious as to be invisible. But once you see it, you can’t un-see it.
PS, the rest of the images are very good (humorous, satirical/parodic, and anti-leftist, what more could a guy want?).