Just-so stories about the relationships between language and culture. (The worst thing is that, while just-so stories about evolutionary psychology are generally immediately identified as sexist/classist/*ist drivel, just-so stories about language tend to be taken seriously no matter how ludicrous they are.)

Well, the Sapir-Whorf hypothesis is the idea that language shapes thought and/or culture, and Whorfianism is any school of thought based on this hypothesis. I assume pop-Whorfianism is just Whorfian speculation by people who aren't qualified in the field (and who tend to assume that the language/culture relationship is far more deterministic than it actually is).