Rule 621 

The 6-2-1 rule is a furry convention hygiene guideline. The rule mandates the following:

6 hours of sleep per night.
2 meals per day.
1 shower per day.

These numbers are lower limits and not intended as upper limits. The third part of the rule is to prevent con funk - all parts help to avoid con crud and concurrent post-con depression.
Source: 6-2-1 rule Wikifur

1: "Oh man, I'm so tired..."
2: "Well, did you stick to the Rule 621?"

Rule 621 by Samadadood July 10, 2018

Rule 621 

Rule 621 states that for every famous person there is at least one fursona based on them.

Rule 621 is named after the furry website e621.net and is a subrule of Rule 34.

Searching Carl Lancaster just beings up a bunch of rule 621 fanart

Rule 621 by The Eerie Red Light December 6, 2017

Rule 621 

If it has animals, there is furry porn of it. A subset of rule 34. Named for the furry imageboard e621.

"My niece couldn't spell Ratatouille so I Googled it for her, and we accidentally found Ratatouille porn. Why, internet, why?"
"Because rule 621."

Rule 621 by laofmoonster August 30, 2013