性行為的基本類型

肛交（anal Intercourse）在此被定義為涉及一個人的陰莖與其他人肛門之間的性接觸。

因為肛門是身體的較敏銳的性敏感區之一，許多男女在性活動中喜歡某種形式的肛門刺激。事實上，當一些個體自娛（自慰、手淫）時，為了獲得額外的刺激，他們可能把自己的手指或一些圓柱形物體插入肛門。因此，在男性之間的性交期間，一個性伴的肛門與另一個性伴的陰莖有時進行直接的接觸，這幾乎不會令人感到驚訝。

一名男子極有可能把陰莖插入其性伴的肛門。但是，與陰道不同的是，因為肛門不分泌自然的潤滑液，使用一些人造潤滑液就是明智之舉了。特殊的水溶劑型軟膏或護膚液是這些潤滑液中最合適和最受歡迎的種類；最好輕巧和小心地把潤滑液塗抹到肛門本身（而不是性伴的陰莖）。此後，緩慢的插入便可開始了。不過，也有一些男子只是喜歡把陰莖在其性伴的兩邊臀部之間[1]摩擦。

雖然肛交可以令性伴感到滿足，但是這種性交並不比人們常常認為的那樣普遍。畢竟，在我們的文化裏，因為肛門的排泄功能，現今許多人仍然習慣於認為肛交是猥褻的和令人厭惡的。（就較小的範圍看，因為性器官與排尿有關，也被想像成令人厭惡的。）另外，也存在強烈的宗教和社會禁忌反對肛交。在一些國家，它甚至是一種犯罪。在這種文化背景下，一些同性性交的男人正像許多異性戀者一樣強烈地反對肛交也就不足為奇了。

最後，我們仍然要申明的是，出於解剖結構的原因，在女性之間不可能存在肛交行為。唯一的例外可能是用皮帶佩戴上一個人造陰莖的女人。不過，這種可能性是理論大於現實，因為女性性伴雙方通常會滿足於其它形式的性刺激。

3. Homosexual Intercourse

Anal Intercourse

Anal intercourse is here defined as involving sexual contact between the penis of one partner and the anus of the other.
Since the anus is one of the more sensitive erogenous zones of the body, many men and women enjoy some form of anal stimulation during their sexual activity. As a matter of fact, some individuals insert a finger or some cylindrical object into their anus for additional stimulation when they masturbate. It is therefore hardly surprising that, during sexual intercourse between males, the anus of one partner and the penis of the other should sometimes be brought into direct contact.
It is very well possible for a man to insert his penis into his partner's anus. However, since the anus, unlike the vagina, does not provide its own natural lubrication, the use of some artificial lubricant is advisable. Special water-soluble creams or lotions are the most suitable and popular of these lubricants, and they are best applied gently and deliberately to the anus itself. After that, a slow insertion can begin. However, there are also some men who simply enjoy rubbing their penis between their partner’s buttocks.
While anal intercourse can be satisfying for both partners, it is not nearly as common as is often believed. After all, most people in our culture are conditioned to consider the anus filthy and repulsive because of its excretory function. (To a lesser extent, the sex organs are also seen as disgusting because of their association with the release of urine.) In addition, there are strong religious and social taboos against contact between anus and penis. In some countries, it is even a crime. Under the circumstances, it is hardly surprising that some homosexual men object to anal intercourse just as vehemently as many heterosexuals do.
Finally, it remains to be stated that, for anatomical reasons, there can be no anal intercourse between females. The only exception would be a female who wears an artificial penis strapped to her body. However, this possibility is more theoretical than real, since female couples are usually content with other forms of sexual stimulation.