Like a saxophone, can be played in several keys as "behen chod", "BBBBBhenchod" or "binchud". Each of these has it's own meaning.
"behen chod" is an insult. It does not mean the same as macha, aliya in South India (all of which means the addresse is one's brother-in-law). Rather, it means that addressee has committed a rather disgusting act of incest a la Caligula, Ptolemy XII and many other infamous Roman kings.
"BBBBhenchod" means the same as above, but now one really means it.
"Bhenchod" is a mild expostulation of suprise meaning, essentially "Oh" or "Wow"
"Binchud" is the same, but used in less vocally expressive parts of the country like Mumbai and Gujarat where time is money and even insults and deprecations need to watch the clock.
Warning: Do not use this word until you know your counterparty
From Maximum City by Suketu Mehta:
I missed saying bhenchod to people who understood it. It does not mean 'sister fucker'. That is too literal, too crude. It is, rather, punctuation, or emphasis, as innocuous a word as 'shit' or 'damn'. The different countries of India can be identified by the way each pronounces this word - from the Punjabi bhaenchod to the thin Bambaiyya pinchud to the Gujarati bhenchow to the Bhopali elaboration bhen-ka-lowda. Parsis use it all the time, grandmothers, five-year-olds, casually and without any discernible purpose except as filler: 'Here, bhenchod, get me a glass of water.' 'Arre, bhenchod, I went to the bhenchod bank today.'