RUSTENBURG, South Africa(AP)—Watch those mouths, boys. Same for fingers, elbows, fists and anything else that could be construed as, uh, universal gestures.

The Brazilian referee and his assistants for Saturday’s England-United States game at the World Cup are brushing up on the lexicon of English-language obscenities.

The crash course in cursing is thanks in part to hot-tempered English star Wayne Rooney, who ran his potty mouth during a warm-up match this week.
 
But swearing a blue streak isn’t the only thing that could lead a referee to toss a player from the World Cup. Obscene gestures and overly aggressive behavior are big no-nos, too, and the refs will be on the lookout.

“In this day and age, I think it’s important to show the referees some respect,” England captain Steven Gerrard said Thursday. “You don’t use any language, because then you’ll be booked and the whole team suffers. You don’t want to fall into that trap.

“We’ve had experience of losing big players at important times.”

On Monday, Rooney was given a yellow card - a warning - after referee Jeff Selogilwe claimed the striker swore at him. This came during a meaningless exhibition game against a local club team, no less.

“He is a fantastic player and we don’t want to take Wayne’s fire away from him because that’s the type of player he is, always on the edge,” Gerrard said. “Wayne himself just has to make sure he controls his frustrations in the right manner - and takes it out on the opposition and not the referees.”

Especially when the referees can understand his every word.

Cursing in soccer is hardly new. Watch any game, and you’re sure to see players uttering some choice words after missed shots, fouls or turnovers. Portuguese, Korean, Greek - nothing gets lost in translation. But referees can’t give out cards for what they think was said, and FIFA requires World Cup referees and assistants to be proficient only in English.

“At the end of the day, you don’t understand half of it,” former Premier League and FIFA referee Graham Barber said. “So what do you do about it? Say ‘I think he swore he at me, so I sent him off?’ You don’t, do you?”

If it’s said in the referee’s native language or English, however, get ready for a yellow card.

FIFA denied reports that match officials have been given lists of swear words. But one member of Saturday’s officiating crew said they’re boning up on English and American curses. Carlos Simon will referee Saturday’s match in Rustenburg, assisted by Roberto Braatz and Altemir Hausmann.

“All players swear and we know we will hear a few,” Hausmann told Brazilian broadcaster Globo Sport.

While their ears will be listening for curses, their eyes will be looking for other ugliness.

There’s an old saying that soccer is a gentleman’s game played by thugs, and players earned that reputation on more than one occasion. Look no further than the final at the last World Cup, when French great Zinedane Zidane was sent off for head-butting Italy’s Marco Materazzi in the chest. Materazzi wasn’t altogether innocent, either, reportedly saying some not-so-nice things about Zidane’s mother.

In a game in 2006, American Brian McBride was a bloody mess after taking an elbow to the face from Italy’s Danielle De Rossi. The suave, seemingly unflappable David Beckham was reviled at home after kicking Argentina midfielder Diego Simeone at the 1998 World Cup, a display of petulance that helped cost England the game.

Rooney gets his own chapter in the book on bad behavior.

At the 2006 World Cup in Germany, England’s mercurial star drew a red card - and automatic ejection - for stomping on Portugal defender Ricardo Carvalho’s groin.

This emphasis on curtailing cursing and bad behavior shouldn’t come as a surprise to any players - English, American or otherwise. FIFA prides itself on its family friendly entertainment, cracking down on anything that could be considered violent or vulgar. It met with each team before the World Cup, reminding players they could be carded or tossed for salty language or obscene gestures.

“It’s a good warning for all of us, just to clean up the game a little bit and watch what we say,” U.S. forward Jozy Altidore said. “Not just for the fans, but for everybody.”

AP Sports Columnist John Leicester and AP Sports writers Ronald Blum and Rob Harris contributed to this report.