Madison Keys was one of the players that used a out of place phrase as a prank during interviews. Photo: Jason DeCrow/AP Photo

NEW YORK There have been raised eyebrows at some of the bizarre and nonsensical statements served up by players during this year's U.S. hardcourt season and on Tuesday it was revealed that American comedian Jimmy Fallon was behind the prank.

"The Tonight Show" host challenged players to casually sneak in the head-scratching phrases into their media interviews and he had no shortage of volunteers who were willing to play along.

Andy Murray and Karolina Pliskova were among those who left their audience bewildered and bemused.

"I used to take cat naps but now I take kitten naps, which are half as long but twice as cute," a deadpan Murray said when asked about his preparations for the tournament.

"I think Serena is so good at just knowing how to use every part of the kayak," Madison Keys said when asked about fellow American Williams.

"Game set match, do the cabbage patch," the typically reserved Pliskova said while letting out a laugh.

Perhaps the strangest comment of all came from enigmatic young Greek Stefanos Tsitsipas.

"Slap your dad and call him Brad," he said rather seriously.

Even the world number ones got in on the act.

Reflecting on his epic Wimbledon final win over Roger Federer, Novak Djokovic provided a catchy insight.

"In the Wimbledon final against Roger.... when the score was deuce, the juice got loose," he said.

The exact phrase was also uttered by Naomi Osaka, although she struggled to keep a straight face during her delivery.