All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is permissible for the husband and wife to enjoy each others body, as Allaah says (which means): {They are Libas [i.e. body cover, or screen, or Sakan, (i.e. you enjoy the pleasure of living with her - as in Verse 7:189) Tafsir At-Tabari], for you and you are the same for them.}[Qur'an 2:187]. Allaah further says (which means): {Your wives are as a tilth unto you; so approach your tilth when or how you will.}[Qur'an 2:223]. However, taking pleasure from each other should be according to the noble, good and general Islamic decencies. There is no text on the prohibition of what the questioner has mentioned, however, it contradicts good moral standards and noble manners, and is far from the natural dispositions that Allaah has created us with. Doing that is touching impurity. Allaah says (which means): {Indeed, Allaah loves those who are constantly repentant and loves those who purify themselves.}[Qur'an 2:222]. This means those who keep themselves above the dirty and the filthy things. Putting a plastic cover on the vagina and then licking it or kissing it, is not sure to avoid some kind of impurity.
Nonetheless, we do not say that it is forbidden as long as there is no impurity that touches the mouth.
Allaah knows best.