It means the KKK (Ku Klux Klan) which was an American white supremacist hate group. The reason 3 11 stands for 3, 11s with 11 being a K, the eleventh letter of the alphabet.
Guy 1: Yoo how do we talk about the KKK without sounding sus?
Guy 2: How about we come up with some secret code with letters from the alphabet and numbers?
Guy 1: I guess we could do 3 11.
Guy 2: How does that mean KKK?
Guy 1: 3, 11s with 11 being the eleventh letter of the alphabet.
Guy 2: Oh that makes sense. Speaking of which should we join the 3 11.
Guy 2: How about we come up with some secret code with letters from the alphabet and numbers?
Guy 1: I guess we could do 3 11.
Guy 2: How does that mean KKK?
Guy 1: 3, 11s with 11 being the eleventh letter of the alphabet.
Guy 2: Oh that makes sense. Speaking of which should we join the 3 11.
by Pork on a Stick December 8, 2019

by Throwaway91090 June 25, 2016

by Qwrety3 December 6, 2020

by Mate4 November 10, 2019

Boy: *gives girl his sweatshirt* I love you!
Girl: Why are you doing this?
Boy: Because it’s November 11!
Girl: Why are you doing this?
Boy: Because it’s November 11!
by J. Dover. 123 November 10, 2019

by Retorted guy October 24, 2019
