What it means
A stan is a die-hard, obsessive fan who defends their idol to the bitter end and follows their every move. To stan someone is to back them with that same fierce, all-in devotion.
Usage examples
"She is a total stan, she knows every lyric and every tour date."
"I stan one artist and one only, do not test me."
"You lot can laugh, but I fully stan her. She hasn’t dropped one bad song yet."
"He stans that footballer so hard he’s in the comments fighting for his life every match day."
Where it comes from
It comes from Eminem’s 2000 track Stan, where the title character is a fan whose obsession turns dark fast. From there, stan stopped being just a name and became internet slang for an ultra-devoted fan. Later, people also turned it into a verb, as in to stan someone.
This expression also appears in