8 Reasons We Never Want to Be Friends With George Clooney, Matt Damon, or Brad Pitt

"I've done some terrible things to Brad Pitt," George joked during an appearance on The Graham Norton Show in 2015, before disclosing what he did to Brad to kick off their prank war. While filming 2001's Ocean's Eleven, he secretly put a bumper sticker on the back of Brad's car in the shape of a pot leaf with the words "F*ck Cops" in hopes it would get him pulled over. Lo and behold it did, and Brad declared war.

To get back at George for the pot plant bumper sticker, Brad saw the perfect opportunity during a Venice Film Festival junket a few years later. He'd been doing interviews for hours, and reporters kept asking him when he was going to marry Angelina Jolie. “He got so sick of the questions that he said, ‘I’ll marry Angelina when George Clooney marries his boyfriend,’” recalled Matt, who was there doing interviews for his role in The Informant at the same time, while talking to David Letterman months later.

Naturally it didn't take long for a journalist to ask Matt if the rumors were true, and since he was happy to help Brad out with the lie, he responded, “Yeah, yes of course he has a boyfriend; we’ve been on him to do it for years." The foreign press didn't pick up on the joke at first, leading a man to strip for George the next day at one of the festival's panels and proclaim his love for him.

Ellen DeGeneres's talk show is now one of the most popular programs on TV, but in 2008 she was desperate to nab one guest in particular: George Clooney. Since he moved into office space on the same lot that her show was being filmed on, she began sending over everything from little gifts to Dolly Parton and some Victoria’s Secret models to try to persuade him to appear. While speaking to Brad via satellite during one of her episodes, he had some helpful advice on how to "catch Clooney."

"This is your problem. . . . Get a bunch of Chippendales dancers," he told her. "He’s yours! Three, four — no less than three. Make one a blonde!" Ellen did exactly as he instructed, but sadly it still wasn't enough. Thankfully when she sent over former Cincinnati Reds players Johnny Bench and Joe Morgan in 2009, George took the bait.

Before getting on set for Ocean’s Twelve in Italy, Brad sent out a memo to the crew in Italian telling everyone that they shouldn't look George in the eye or even speak to him, because he's such a serious actor and he'll get upset. For George, who Brad says is "like the mayor" on set, it was two weeks of confusion.

One of George's most tried-and-true methods of pranking his friends is by stealing stationery with their official letterhead, which he then writes absurd letters on and sends out to fellow celebrities. "I've sent letters to lots and lots of people from Brad. . . . I always let [him] know around two years later, and [he's] like, 'Are you kidding me?!'" he told Graham Norton. Two of the funnier instances of it happening involved Tom Cruise and Don Cheadle.

"He wrote [Tom] Cruise saying I wanted to do the sequel to [Interview With a Vampire], but I hope he didn't mind that I wanted to recast Lestat," Brad laughed during an interview with Australia's The Project. "Then he wrote something to our friend Don Cheadle, who's been trying to direct this book on Miles Davis for forever. It said my production company and I were sorry, but we were going to do a Miles Davis movie. He got dirty!"

Matt wasn't safe from George's fake letter prank, either. To get back at Amy Poehler and Tina Fey for their hilarious Gravity joke at the Golden Globe Awards ("Gravity is the story about how George Clooney would rather float away into space and die rather than spend one more minute with a woman his own age"), he sent them an upset letter "from Matt" (written on the Bourne Identity star's letterhead) complaining about all of their jokes.

"I sent her a letter saying, 'Dear Tina, listen, it’s from Matt,'" he explained at a SiriusXM Town Hall event later on. "It just said, '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.'"

Luckily the comedians saw through his shtick. They sent Matt two fruit baskets, each with their own note. While the first offered an apology for hurting his feelings, the second made it clear they weren't messing around: “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 f*ck up. We are not some easily confused starlets here. We are grown-ass, professional comedians. Please accept this fruit as a token of our sincerity. Best wishes, Elizabeth Tina Fey, Amy 'Boston' Poehler."

When Matt confessed to George he wanted to lose a couple of pounds before they began production on their 2014 movie The Monuments Men, George saw his opportunity. “Over a period of about a month and a half, he’d come and go from the set," George said at a panel for the movie. "Every time he went away I’d have the wardrobe girl take in his uniform like a half an inch. He was eating great, and then his pants were getting tighter." Naturally it drove Matt crazy.

Using some of the leftover stationery he'd stolen from Brad, George decided to deliver Meryl Streep a helpful present. "I sent Meryl Streep a letter from Brad with a big thing of CDs by a dialect coach,” George fondly recalled. “It said ‘I hear you’re going to be doing The Iron Lady soon; this guy helped me with my dialect in Troy, so I thought this would help. She was very confused."