@dmd @ChippySuave
Looked it up. Found this to be very interesting! Learned something new today!
"Leet speak" predates 1337 culture; leet speak ("elite speak") is a stylistic way of spelling English letters by using numbers and special ASCII characters on your keyboard. This is a cultural expressiveness that spawned when 1980's hackers wanted to cloak their websites and online conversations from being found.
https://www.lifewire.com/what-is-1337-leet-4089946