Title text:
In 1899, people were walking around shouting '23' at each other and laughing, and confused reporters were writing articles trying to figure out what it meant.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3184/
For millennials, like me: 1337 means "LEET" which is short for "Elite".
Ragebait. Millenials are like 40 and have back pain.
I can confirm you can in fact get back pain before the age of 40
Batman can confirm too.
Source: Knightfall.