The humble watermelon. The epitome of summer. But how do you know if it's perfectly ripe? Well, one theory is that if you knock hard on the outside, the sound you hear will help determine if it's ready to eat.

其貌不扬的西瓜象征着夏季。但你怎么确定西瓜是否熟透？有种理论是，用力敲敲西瓜皮，听听声音，这能帮你确定它们是否完全熟了。

That theory lead to a huge online debate in China about what kind of people engaged in the art of 'watermelon knocking'?

这种做法近期在中国的网络上引发热议，大家争相讨论哪些人爱“敲西瓜”。

The discussion, which thousands of people contributed to on the Chinese micro blogging site Sina Weibo, was kicked off by an obscure event thousands of miles away in Italy.

数千人参与了新浪微博上的这次大讨论，而引发这次讨论的是遥远的意大利的一件小事。

It all began when a Chinese social media user posted the picture below of a sign in an Italian supermarket asking customers not to knock on the watermelons. The sign was stuck in a crate full of watermelons which read: "please stop knocking on the watermelons, they will not respond to it!"

一位中国社交网站用户发布了下面这张照片，照片上，这家意大利超市挂出一则标识，要求顾客不要敲西瓜。这则标识插在装满西瓜的板条箱里，其上写道：“请不要再敲西瓜了，西瓜不会回应你。”

There is no indication that the supermarket was targeting this message at customers with Chinese heritage. The sign was in Italian not Mandarin. But somehow it was taken as an attack on a practice which some Chinese observers regarded as being unique to their national customs.

没有迹象表明超市挂出这则标识是针对中国顾客。标识是用意大利语写的，而不是汉语普通话。但不知为何这被当成了对敲西瓜这种行为的攻击，而一些中国评论者认为敲西瓜是中国人独有的习惯。

According to What's On Weibo, the photo was widely shared after Chinese media outlets reported that the notice was aimed directly at Chinese customers. But some social media users were quick to establish that the art of knocking watermelons is not exclusive to China and is in fact universal. The viral photo was originally posted by a user on Weibo who calls himself 'Isolated Guardian'. He is allegedly a Chinese man living in Milan. The photo has since been removed from his page.

根据微博上的信息，在中国媒体报道称这则标识针对的是中国顾客后，这张照片迅速火遍中国网络。但一些社交媒体用户很快发现敲西瓜并非中国独有的现象，其实在全球都非常普遍。最初上传这张照片的是一位名为@孤岛守护者的微博网友，据说是一位居住在米兰的中国人。后来他将照片在其个人主页删除。

Many shared jokes aimed at the supermarket sign.

很多网友分享了有关这则超市标识的笑话。

Some people shared photos of themselves listening for a response from watermelons.

一些人分享了自己听西瓜“回应”的照片。

The topic of watermelons is another example of how some people in China are concerned about how they are perceived around the world.

敲西瓜这一热门话题是一些中国人关心外国人如何看待他们的又一例证。

Online users are keen to show they know better, especially on the subject of watermelons.

网友们热衷于表现出自己知道的更多，特别是关于西瓜这件事。

Others pointed out that the concept of watermelon knocking has been passed down from their parents.

还有人指出敲西瓜是爸爸妈妈传下来的方法。

A quick online search will reveal that Chinese social media users are not alone in their thinking. Watermelon knocking and listening for a hollow sound is indeed a near universal concept. A vast array of videos and blogs provide with advice on how to pick a good watermelon. It even appears in film and animation. Popular Russian cartoon, 'Nu, pogodi!' included watermelon knocking as part of an episode.

在网上快速搜索一下就会发现，不仅仅是中国的社交媒体用户这样想。敲西瓜、听回声其实是一种普遍现象。有很多视频和博客都给大家提供了如何挑选好吃的西瓜的建议。敲西瓜这种行为甚至还出现在电影和动画片里。流行的俄语卡通片《兔子，等着瞧！》中也有敲西瓜的情节。

One video comically claimed to have a magic formula but the end result was not very convincing. There's even a smart phone app designed by Chinese university students to you help you in your endeavour to find the ideal watermelon.

一段视频中滑稽地说，有个挑选好西瓜的魔法公式，但其结论并没那么有说服力。几位中国大学生还发明了一个帮人挑选好西瓜的智能手机应用。

There are no absolute guarantees about what to do when it comes to choosing fruit. But at the risk of causing an international diplomatic incident we would suggest there some common ground about what to look for to choose the perfect watermelon.

在挑选水果的时候，没有什么万全之策。但冒着引发国际外交事件的风险，我们给您提几条关于挑选好西瓜的建议。

Feel the weight of the melon. The heavier the better

感受一下西瓜有多重，越重越好。

Press on the watermelon. It should feel firm and if it springs back, it's ready to eat

在西瓜皮上按一按，应该很硬实，如果按下去后能恢复原状，就熟透了。

Look at the markings on the melon. A yellow patch on one end indicates it's ready

看下西瓜上的条带。如果一端发黄就是熟了。

Of course if that all that fails, you could always, knock and wait for a reply.

当然如果这些都没用，你就可以敲敲西瓜，等它回应。