H number

Drug lingo mainly used by inmates in the prison system to denote when the last time that they have gotten high on heroin.

A joke that most people don't get that's mostly used in purposes of baiting switch.

H Is A Number (or H-roll) first became a thing on August 13th, 2020 when some users had a general discussion on discord, some people were talking about age restrictions.

"Users under 13 cannot use discord" someone said.

Of course, people were joking about someone being underaged after that message. Another user replied with:

"Age is a number, not a problem"

And that's where the joke basically began...

Some hours later, a user by the name of "undR/H cancer not allowed" posted a morse code that once translated said this:

"H is a number, just got H-rolled"
(There's numerous ones but this one is the most well known message)

From then on, the joke "H is a number" is not just used to warn moderators that users under 13 are on their discord server, but it's also used for morse code conversations, ending with the phrase "H is a number" or "-H" as a joke at the end of the message. Of course it's not just used on discord only, since it's a meme, it can spread from person to person.