“You must be new here” is a phrase used to call attention to incoming noobs in discussion forums or social networking sites. The expression has been also commonly associated with a still image of Gene Wilder as Willy Wonka from the 1971 film “Willy Wonka & The Chocolate Factory.”
The colloquial usage of “must be new here” has been noted in popular films and TV comedy series for many years, with the earliest mentions found in an episode of the 1967 British TV series The Prisoner and more recently in an episode of the FOX sitcom series “Titus” that aired in 2000.
Number 6: [referring to the chess game] Why do you use people?
Chessmaster: Some psychiatrists say it satisfies the desire for power. The only opportunity one gets here.
Number 6: That depends what side you’re on.
Chessmaster: [quickly] I’m on my side.
Number 6: [quickly] Aren’t we all.
Chessmaster: You must be new here. In time, most of us join the enemy – against ourselves.
- The Prisoner, Checkmate
On the web, the phrase has been used in the comments of numerous blogs and news sites as a response to stereotypical newbie questions or as the title of forum threads addressed to the newcomers, as seen in a Badminton Central forum thread in October 2002 and a Geek Culture forum thread in July 2004.
Throughout the 2000s, the phrase became widely used in the discussion forums and chatrooms in mocking redundant or obvious comments, most notably on Slashdot and 4chan where cultural elitism is more tolerated. The earliest archived threads on 4chan were posted in 2007.
“You must be new here” can be also shortened in the form of acronym “YMBNH,” according to the Urban Dictionary entry submitted on July 21st, 2006.
YMBNH: Shorthand for You Must Be New Here; used in internet chat forums to slightly mock posters of redundant/obvious comments.
Similar reaction images stemmed out of an exploitable macro series titled “Condescending Wonka”  which features a still shot of Gene Wilder as Willie Wonka accompanied by patronizing captions like “You must be new to this.”
The Willie Wonka instance initially spread through Gizmodo forums and Tumblr in January 2011 and the image has since become a common response to new member who may not be fully aware of the rules or social cues of the site they are interacting with.
Search for “You must be new here” began in August 2010 and has been increasing, with popularity spiking in February and November 2011.