George Clooney's funniest pranks in Hollywood

He's one of the most popular actors in Hollywood for over two decades. Yet, there is a side of George Clooney that the general public may not know about. His Hollywood colleagues are all too familiar with that side though. Check out George Clooney's pranks!

You could say it's a bad habit: that of constantly playing jokes, sometimes really harsh ones, on his (celebrity) friends. Who've been the victims so far? Let's have a look!

Let's start with his favorite victim, Brad Pitt, for whom he has reserved several jokes over the years. It all began during the filming of 'Ocean's Eleven' in 2000 when the two really got to know each other.

As he recounted on 'The Graham Norton Show', one day, George came up with the idea of attaching a sticker (the kind that is not easy to take off) in the shape of a marijuana leaf with the words "F Cops" on the back Brad Pitt's car...

And this was not the only prank he pulled on his close friend. Around the time that Brad Pitt married Angelina Jolie, Clooney began a bizarre and elaborate joke that lasted for several years. As he confessed on 'The Graham Norton Show,' Clooney would write letters to his Hollywood colleagues, signing them with Brad Pitt's name.

George Clooney's letters claimed several victims in Hollywood. The most hilarious was the one addressed to the accomplished actress Meryl Streep. Attached to the letter was a package of CDs with lessons for learning every type of dialect.

In the letter, the fake Brad wrote to the wonderful actress (who certainly doesn't need lessons) that these CDs would help her to play 'The Iron Lady' (the biopic about Margaret Thatcher), just as they had helped him play a Greek warrior in 'Troy'!

Clooney told Graham Norton that he only revealed the truth to the victims of his letters years later...

Another joke that went around the web and was reported by the Daily Mail, was the one Clooney pulled on the producer of the Ocean's saga, Jerry Weintraub. The producer, on the right in this photo, recounts: "I had a gold silk shirt... a very expensive gold silk shirt... [that] Clooney hated. Once at the Bellagio when we were doing Ocean’s, I was having drinks with the guys, and Clooney sneaked into my closet and stole the shirt."

"That September, for my birthday, I received a big box wrapped with ribbon, and in it was my gold shirt," Weintraub continues. "On the back, Clooney had drawn a picture with a black marker of a giant p e n i s, and he’d had everyone who participated in a charity golf tournament for prostate cancer in Las Vegas sign it, too. There were 30 signatures... Brad Pitt, Matt Damon, Don Cheadle, Wayne Gretzky..."

But the joke on Jerry Weintraub didn't stop there. One day, while the producer was receiving a back rub, Clooney silently took over from the masseuse, warmed his hands, and gave him a very strong slap on his behind. Brad Pitt was his accomplice who photographed everything! The producer was not too ashamed to recount the story himself on 'The Ellen DeGeneres Show.'

Even though Clooney loves playing pranks, it's best not to do them to him. Tina Fey and Amy Poehler know something about that. At the 2014 Golden Globes gala, they decided to target the charming actor, as well as many other guests, including Matt Damon. For example, the two hosts had defined the latter as "the street cleaner among the real stars."

About George Clooney who, at the time, was getting a lot of awards with the film 'Gravity', the two presenters said that the actor would rather float in space than spend time with a woman the same age as him.

Clooney was not pleased at all. His response? He wrote a letter to Tina Fey and Amy Poehler on behalf of poor Matt Damon!

In the fake letter, he wrote: "Look, it sounds hypocritical because I laughed at the jokes about George and Leo, but you know, that’s sort of what people think about them. But when you called me a garbage man, it just seemed like low-hanging fruit, it just seemed like an easy joke. And you know, I don’t want an apology, I don’t want anything else, I just want you to know that my kid now calls me the garbage man." This letter was released by Hollywood Reporter.

During an interview on the David Letterman Show, Matt Damon said that, out of the blue, Tina and Amy sent him two fruit baskets with two letters. He was unaware of the reasons for them doing that.

In the first letter they apologized to him, while in the second, as reported by CBS News, they wrote: ""If your note is part of some George Clooney prank, as I very strongly suspect it is, you A-list amateurs are going to have to step it the [expletive] up. We are not some easily confused starlets here. We are grown-a..., professional comedians."

And there were more victims of George Clooney's pranks. His old friend Richard Kind discovered one time, years ago, that it is better not to let Clooney stay at your home. He had generously offered him so after Clooney's divorce from Talia Balsam.

Clooney told 'The Howard Stern Show' that, in those days as a guest, overcome by boredom, Clooney made Kind believe for several weeks that his cat suffering from constipation. The conniving guest secretly cleaned the cat's litter box every day, which caused his friend to get very worried about the poor animal!

The prank lasted several weeks. Then, George Clooney finished it off by leaving an enormous piece of excrement, totally disproportionate to the small cat, in the litter box. Richard Kind was amazed!

Once at a dinner party, Sandra Bullock saw George Clooney shirtless by the pool. He told her, invitingly, that he was going to jump.

So, the actress, another guest, and Clooney hold hands to jump into the pool together. Clooney said that on the count of three, they would jump. He counted and... only Sandra Bullock jumped into the pool.

According to LA Times Magazine, Clooney pranked one of his teammates during his last day on the series 'E.R.' He changed the plates of the actor's car and instead put one that said: "Honk if you like P...y". When the victim left the set, he thought everyone was honking at him to greet him.

One of the few victims who had the courage to respond to Clooney's terrible pranks was Brad Pitt. During an interview available on the YouTube channel 'Brad Pitt Online,' he said that he took revenge on his friend while they were filming 'Ocean's Twelve' in Italy.

He left posters around town, warning people in Italian against Clooney's alleged vanity. As Clooney remembers in the 'Ask Me Anything' interview on Graham Norton's show: "He had a flyer sent around saying George only wants to be called by his character's name Danny Ocean." The flyer also instructed locals to not look the actor in the eyes. And of course, the crazy demands made local news.

George himself admitted years later on 'The Howard Stern Show' that this was one of the harshest pranks he had received. The posters were so well made that Italian newspapers at the time started calling Clooney "Il Divo" ('the arrogant star') which really hurt his feelings!