It's Such a Gas! 是那種“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間，人體功能的自然生理現象一直是低級幽默中的一個熱門話題，這其中尤以放屁為最。屁，是從肛門排出的氣體，通常伴隨一聲巨響、一陣振動感，以及一股難聞的臭味。它也是消化系統進行化學作用的過程中最常見的副作用之一。

屁的學名是“腸胃脹氣”或是“腸胃氣脹”，不過英語里有一套令人印象深刻的生動說法來形容這種消化氣體的爆發。譬如我們可以說“起風”，“平地一聲雷”，“瓦斯漏氣”，“臭氣飛彈”，“踩到噗噗鴨”，或“切奶酪”。

不管人們決定怎樣稱呼它，健康的人一天平均會放16次屁，大多是在睡覺時放的。盡管從整體而言女性放屁較少，但實際上女性放的屁其實跟男性一樣多。大部分其它的哺乳類動物也放屁──讓人擔心的是大象可能是最常放屁的。

一個人的屁臭不臭，取決于他或她最近吃了什么。如屁的組成氣體中包含大量的硫化氫，就會發臭。硫化物攝取得越多，硫化氫的產量也會越多。含有豐富的硫化物的食物包括豆類、奶酪、卷心菜、蛋和蘇打水。

飲食外的其它因素則決定屁的多少和組成氣體的相對比例。比如，消化道內的細菌種類和人所吸進的空氣量就是影響因素之一。容易緊張的人可能會吸進大量空氣，在血液還沒吸收前，空氣已經快速通過了消化系統。空氣在體內停留的時間越久，尚未放出的屁中含有惰性、無臭的氮氣的比例就越高。

由于這些因素的綜合影響，便產生了種種不同的腸胃脹氣。了解這些相關因素將有助于人們對其加以控制。不過，可別對放屁過于緊張。大家都知道，每個人都會放屁，即使皇帝和皇后也不例外。