The 'Bourne Identity' star was convinced his good friend and infamous joker George had gone into his wardrobe and swapped his suit for a smaller size - but he was dismayed to discover he had simply piled on the pounds.
He admitted: "A couple of years ago I hadn't been working out and I'd got kind of fat. I had to go to a function and when I tried on my suit, it was too tight.
"My immediate thought was that my buddy George Clooney had hired someone to get into my closet and cut down my clothes. I seriously thought that - until my wife said, very gently, 'Do you think it might be that you've put on some weight?' "
The 42-year-old star's small suits aren't the only wardrobe malfunction he has faced, as he admitted his favourite pair of battered boots are a constant cause of contention with his wife, Luciana Barroso.
Asked what his worst habit is, Matt admitted: "Probably my inability to clean out my closet. I have a pair of old boots that I've been wearing since 2008 that I just can't get rid of.
"I love them because they're the most comfortable boots I've ever owned, so I keep on getting them re-soled. But my wife hates them and thinks they're the ugliest things she's ever seen."