I really love fruits. Especially something like pineapple, all kind of berries and oranges. I could easily eat nothing but fruits for a few days. So I just thought about the issue if a diet like this exists? I mean a diet which allows you to eat nothing but fruits. And if it does, has anyone ever tried it?

any diet of one thing only is going to have you missing other key nutrients -in this case - protein and fats...

again I'll say it- you seem to be looking for tricks... and short cuts - keep track of your calories and exercise and you will drop the pounds

Mal is right, you will not get enough protien, fat or calcium, along with other minerals that are necessary for a properly functioning body. You can incorporate fruits into a low calorie diet since they are low in calories and high in fiber. But a diet with only fruit, I would not recommend.

great advice

There are some fruits are good for your diet such as Apples and berries contain pectin. Pectin restricts the amount of fat the cells can absorb and forces the cells to discharge fatty deposits.
And Citrus fruits contain high concentrations of Vitamin C. Vitamin C burns fat by liquefying it. This makes it easier for the body to flush fat from the system.
But keep track of your calories and exercise are important! Mal is right!