It's Such a Gas! 是那种“臭屁”啦！

Natural bodily functions are a popular theme in lowbrow humor the world over, especially among adolescent boys, and none more so than farting. A fart, which is the expulsion of gas from the anus, is often accompanied by a loud noise, a vibrating sensation, and an unpleasant odor. It is also one of the most common side effects of the chemical processes of the digestive system.

Its scientific name is flatus or flatulence, but the English language has an impressive range of colorful terms to describe the explosive emission of digestive gas. We can, for instance, break wind, drop one, pass gas, let one fly, step on a duck, or cut the cheese.

Whatever he or she chooses to call it, a healthy person breaks wind an average of sixteen times a day, and most often when asleep. Females fart just as much as males, though on the whole less extravagantly. Most other mammals fart too, and—a worrying thought perhaps—elephants do it the most.

Whether or not a person's fart smells depends on what he or she has been eating recently. If the combination of gases that make up a fart includes a significant amount of hydrogen sulfide, then it will stink. The more sulfur a person consumes, the more hydrogen sulfide is produced. Foods rich in sulfur include beans, cheese, cabbage, eggs, and soda.

Other factors besides diet determine the amounts and relative proportions of fart gases. The type of bacteria inside the digestive tract and the amount of air a person has swallowed will affect the outcome, so to speak. A nervous person might swallow a lot of air, which then moves quickly through the digestive system before the blood has a chance to absorb it. A potential fart will contain a greater proportion of inert, non-odorous nitrogen, the longer it is held inside the body.

These variables combine to produce flatulence of varying quality and quantity. Understanding these contributing factors can help a person control them. Do not get too flustered about farting, however. As they say, even kings and queens do it.

世界各地，尤其在青春期男孩之间，人体功能的自然生理现象一直是低级幽默中的一个热门话题，这其中尤以放屁为最。屁，是从肛门排出的气体，通常伴随一声巨响、一阵振动感，以及一股难闻的臭味。它也是消化系统进行化学作用的过程中最常见的副作用之一。

屁的学名是“肠胃胀气”或是“肠胃气胀”，不过英语里有一套令人印象深刻的生动说法来形容这种消化气体的爆发。譬如我们可以说“起风”，“平地一声雷”，“瓦斯漏气”，“臭气飞弹”，“踩到噗噗鸭”，或“切奶酪”。

不管人们决定怎样称呼它，健康的人一天平均会放16次屁，大多是在睡觉时放的。尽管从整体而言女性放屁较少，但实际上女性放的屁其实跟男性一样多。大部分其它的哺乳类动物也放屁──让人担心的是大象可能是最常放屁的。

一个人的屁臭不臭，取决于他或她最近吃了什么。如屁的组成气体中包含大量的硫化氢，就会发臭。硫化物摄取得越多，硫化氢的产量也会越多。含有丰富的硫化物的食物包括豆类、奶酪、卷心菜、蛋和苏打水。

饮食外的其它因素则决定屁的多少和组成气体的相对比例。比如，消化道内的细菌种类和人所吸进的空气量就是影响因素之一。容易紧张的人可能会吸进大量空气，在血液还没吸收前，空气已经快速通过了消化系统。空气在体内停留的时间越久，尚未放出的屁中含有惰性、无臭的氮气的比例就越高。

由于这些因素的综合影响，便产生了种种不同的肠胃胀气。了解这些相关因素将有助于人们对其加以控制。不过，可别对放屁过于紧张。大家都知道，每个人都会放屁，即使皇帝和皇后也不例外。