J is an APL language. APL is the coolest language you’ve never heard of. It’s mind blowing in the same way people talk about Lisp, but more so since the concepts are so alien to most programmers.

bla3 figured out that it's because the link text "Jd" is so short, and people are clicking the upvote button by mistake. https://news.ycombinator.com/item?id=30906989