Why is sup slang?

"Sup" is slang for "What's up?" It's a casual greeting that's used in informal situations. It's a shortened form of "What's happening?" or "What's going on?" and became popular in the 1990s.

Here's why it's considered slang:

* Informal: It's not appropriate in formal settings like business meetings or when speaking to someone you don't know well.

* Shortened: It's a contracted version of a longer phrase, which is common in slang.

* Casual: It's used to show a relaxed and friendly tone.

While "What's up?" is still considered the more proper way to greet someone, "Sup" is widely understood and accepted in informal settings. It's a common way to show that you're friendly and approachable, especially among younger generations.