The word Chod relates to rapists? That's news to me.
Can't say I'm vey connected with my heritage but my family and 14 extended swears so much, it would be weird if they threw around the word rape like that. Imagine someone saying "তুইতো সবারই চডোছ" (you rape everyone) instead of (you fuck everyone); to imply someone is a whore/slut.
বড় means husband, বড়চড would mean Man-fucker in this context, add া to make it an action, বড়চডা = gay sex.
Please correct me if I'm wrong, the bengali community where I live now almost never swear, like you said, educated people don't say it.