https://en.wikipedia.org/wiki/Illegal_number :>

You can literally arbitrarily associate any number to anything and ban it based on that, which they did:

> In 2012, it was reported that the numbers 89, 6, and 4 each became banned search terms on search engines in China, because of the date (1989-06-04) of the June Fourth Massacre in Tiananmen Square.

> Due to the association with gangs, in 2012 a school district in Colorado banned the wearing of jerseys that bore the numbers 18, 14, or 13 (or the reverse, 81, 41, or 31).

> In 2017, far-right Slovak politician Marian Kotleba was criminally charged for donating 1,488 euro to a charity.

It's closely related to hate speech laws where the only requirement is perceived threat. Fun times. :D