It is a joke and a real alternative.
The joke is that often when someone proposes using BY-NC, someone else will jump in and explain why they should use BY-SA instead. This forum is new, but you can see many instances of that on CC mailing lists.
It is also a real alternative, but will take some rethinking on your part. If your bottom line is simply preventing anything that looks like commerce around the content, NC does that, but it also discourages uses that you might want and that would be good for the broader commons, and there is a fair amount of disagreement about what actually constitutes "noncommercial" use.
The BY-SA people would argue that you shouldn't really want to prevent any and all commerce, but to ensure that content remains in and builds the commons, which is what BY-SA does. If a commercial entity builds on work but is forced by the license to contribute it back under the same license, that should be for the good, unless you just hate commerce -- or something along those lines.
If you're interested in that perspective I suggest checking out http://freedomdefined.org/Definition and http://en.wikipedia.org/wiki/Copyleft -- and their perspective on NC at http://freedomdefined.org/Licenses/NC