It took almost 20 years, but "Stan" is now officially the word that rap fans have long used it as.
"Stan", of course, comes from Eminem's 2000 hit 'Stan,' which is about an obsessed and deranged superfan.
The Oxford English Dictionary is now recognizing Stan as both a noun -- "an overzealous or obsessive fan of a particular celebrity" -- or a verb -- "to be an overzealous or obsessive fan of a particular celebrity."
The OED explains the origin of the word as "early 21st century: probably with allusion to the 2000 song 'Stan' by the American rapper Eminem, about an obsessed fan."