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/
I was reading Wikipedia about the origins of 23 and came across this neat tidbit:
On the RMS Titanic there was a watertight door on E Deck numbered 23 which was informally called the "skidoo door" according to the testimony of the Chief Baker Charles John Joughin.