Punani is a term for the female genitals, possibly derived from the Indian term punany. In the Kama Sutra the word is used to refer to the female genitalia, and commonly used in north India.
Indian workers in the Caribbean in the early 20th century passed their vernacular on to the locals (cf. ganja), thus Jamaican Patois uses the term for the vagina or vulva.
An alternate (or parallel) etymology is derived from the Hawaiian language term puanani, "beautiful flower".
References
Punani Wikipedia(Text) CC BY-SA