In the first place, it should be noted that a Muslim is a person of a clean heart and tongue. He never utters words of obscenity or vulgarity, since the Prophet (peace and blessings be upon him) said: “The believer does not slander, curse, or speak in an obscene or foul manner.” (Reported by At-Tirmidhi)
However, if a husband and wife found it attractive to them during intercourse to say some words that are not up to the standard (i.e., they cannot be said in public) with the intention of provoking their desire, it is permissible for them to do so as long as they do not utter them in any other situation and they are sure that no one will hear them.
Sheikh `Abdul-Karim Al-Khudair, a prominent Muslim scholar, issues the following fatwa: “A Muslim should refrain from obscenity in all his dealings, whether that has to do with words or deeds, but if he cannot reach a permissible objective without mentioning something that people usually feel too shy to mention, then it is acceptable. It says in the hadith of Ma`iz that the Prophet (peace and blessings be upon him) mentioned some words that he did not ordinarily use. But if there is no need for that and those words are not unlawful, such as swearing and insulting, then it is better not to say them. In that case they are more likely to be reprehensible (makruh). So, in that case there is nothing wrong with saying what was mentioned in the question, so long as the husband and wife do not use the same kind of words in front of their children or anyone else.”
Sheikh Muhammad Saleh Al-Munajjid, a prominent Saudi Muslim scholar and lecturer, adds: “It is permissible for both husband and wife to say whatever they want in order to provoke desire during intercourse, and that does not have to be something that was narrated in the Sunnah, but it is not permissible to say anything that is forbidden in Islam, such as lies or slanderous words. But with regard to mentioning the genitals by their colloquial names or other things that provoke desire in word or deed, the basic principle is that it is permissible.
Some of the scholars are of the view that this is reprehensible, and they regarded it as contrary to proper etiquette. But the correct view is that it is permissible. Even if we accept that it is reprehensible, then that ruling may be lifted when there is the least need for it, and the need here is obvious.
If it is permissible for both spouses to touch each other’s private parts, look at them and enjoy it, then it is more appropriate that they permitted to call them by names that will provoke their desires, and the converse is also permitted.”