Depending on where you live you've probably seen them: T-shirts and tops with communist motifs. The ones you're most likely to be familiar with are T-shirts with the portrait of Che Guevara. Those have been around for quite some time now. A more recent design is the five-pointed star, not necessarily in the right colors (should be yellow on red). The next step up is the hammer-and-sickle symbol. While the star might concievably stand for other things or be purely decorative, this symbol is inarguably communist. The most extreme version I saw recently on a guy in town who had a hammer-and-sickle t-shirt with the abbreviation "CCCP" written below it.
So, why are those people walking around in that stuff? Because they're all die-hard communists with a need to advertise their political orientation? That's a bit unlikely.
It's a fashion trend, of course. For some reason it must be incredibly stylish right now to dress yourself like that. But why would anybody want to wear or produce those garments?
I have a little theory as to why: I suspect it's capitalism trying to assert its final victory over communism, by degrading its symbols to fashion statements without any political message. Thus it degrades the entire idea of communism to something as transistory and meaningless as fashion.
Another thought: Depending on your views on communism, this is no better than t-shirts with swastikas on them, which are not usually seen outside of neofascist subculture. (Poor swastika. It's actually a quite beautiful design, but it'll probably be tainted for a long time yet.)