2. John McEnroe
“You cannot be serious!” instantly became the line that defined McEnroe’s life. He even used the quote as the title of his biography after he retired. The catchphrase materialized during Wimbledon in 1981. The British tournament is notorious for its strict rules and code of conduct, while McEnroe was a fiery personality. In short, they weren’t a match made in heaven.

He played Tom Gullickson in a game where the umpire ruled that his serve was out. The US tennis star instantly erupted with one of tennis’s most famous tantrums and began with that immortal line. He continued lambasting the official for several moments and outraged the Wimbledon organizers in the process. They even broke with tradition by refusing to make him a member of the All-England Club.