13%

13% is term referring population of African-Americans in United States.

It's used when blacks commit crime on Internet

A racist dog whistle used by white supremacists to refer to black crime statistics without examining why the statistics are the way they are.

finally considered a teenager and knows all the perverted jokes of the world

A number commonly known for superstitious beliefs about it being unlucky. Originally it was a holy number, but somewhere along the way it was hijacked and portrayed as unlucky. Fear of this number is called triskaidekaphobia.

13s (13er in German language) are all people, who were born at a date, when the amount of milliseconds of the current system time had 13 digits. That includes people that were born after September 2001 (until 2286, just in case).
Other than the cool 12s, the average 13s is not very cool and shows a remarkably immature behaviour on the internet. 13s like embarrassing themselves on TikTok or similar platform, they like Fortnite dancing in public and are overall just cringe in chats.

Thirteen stands for M, the thirteenth letter of the alphabet. M is for Mexican Mafia. Any real Mexican gang that lives in S. California starding from Bakersfield and down all the way to San Diego should be affiliated with 13.

The most annoying age for any teenager, when s/he is stuck in the awkward first year of being an adolescent.