Title text:
Wait, what do you mean, 'dark matter'? It's not dark, it interacts with high-energy gamma rays ... right? Oh jeez, did I forget to make it interact?
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3263/
Got it: dark matter is Romulan.
Given that it passes through ordinary matter almost entirely undetected, I'd say it was more like the phasing cloak invented by the Federation.
You know, the one that was never heard of again after the episode that featured it.