What began as an outburst of temper against a referee's call at Wimbeldon in 1981 became an iconic expression of incredulity once it was captured by the on-line digital culture. There are many variations. Video clips on YouTube, t-shirts, multiple LOLcats macros, even a parody by McEnroe himself years later in a car commercial.

Released into the wilds of the internet, "You can NOT be serious" has taken on a life of its own.