I just came up with that name a couple days ago. Didn't check what alternative meanings it might have. I've been hacking on it since 2012. This project has gone by more than one name in the past. I easily get bored of staring at the same old name after awhile.
Even though the obscene meaning shows up at the top of search results, it is not a common idiom, and the rest of the search pages do not reflect the obscene meaning.
However, this HN page does show up in the fifth page of search results, so maybe we can take the opportunity, right here and right now to change the main meaning to a more useful, less obscene one :) !