So a bunch of techbros all had XKCD cartoons memorized by the numbers in their perma-links
"XKCD number 570," one would say
And the rest would chuckle, getting the reference, but not laughing hard, because the jokes were all old and stale
So when I noticed this, I said, "XKCD number a million"
And they all laughed uproariously
"We've never heard *that* one before," they said