Eating watermelon has a similar effect on the body to Viagra, according to researchers in the US.
It's down to a chemical called citrulline which is found in the juicy fruit.
Citrulline is an organic compound which affects the body's blood vessels in the same way as the sex enhancement pills.
It helps relax the blood vessels which means blood gets around the body more easily.
The research comes from the US' Texas Fruit and Vegetable Improvement Centre.
Dr Bhimu Patil led the research. He said: "We've always known that watermelon is good for you, but the list of its very important healthful benefits grows longer with each study.
"Watermelon may not be as organ specific as Viagra... but it's a great way to relax blood vessels without any drug side-effects."
It's also claimed watermelons are good for your heart and immune system.
The vast majority of watermelon (92%) is made up of water. But the remaining 8% is loaded with the anti-oxidant lycopene which is also good for your skin.