I have fun with these kinds of people - there are *so* many ways to respond.
I would begin by (as someone else said) asking them to specifically quote the chapters and verses that they are using to condemn you - most of them have never read the bible and this one question will shut them down.
If they can quote a verse it may be Deuteronomy 22:5. A through examination of that verse as has been done in Gill's exposition of the bible and by other bible scholars tell us that verse refers to avoiding military duty by men dressing as a woman, or tricking your way into being able to fight by women dressing as a man.
If they drag out "clobber verses" verses from Levicitus you can ask them if they are *really* suggesting that we should live by those verses, which applied only to the tribe of Levi who were priests. If the answer is yes then you can point out that Leviticus forbids A) shaving, B) having tattoos, C) eating shellfish, D) not killing disobedient children, E) eating fat, F) working on Sunday, G) selling land permanently - and so on. There are 76 prohibitions in Levicitus, many of which make no sense in today's society. Once you have pointed out the absurdity of trying to live by Leviticual law, ask them if they observe and follow all of the laws set forth in those verses? No? Then isn't it being hugely hypocritical to cherry pick verses from Levicitus and require other people to live by them? You gotta walk the walk if you expect others to do so.
And then you can bring up Luke 6:37 - "Do not judge, and you will not be judged. Do not condemn, and you will not be condemned. Forgive, and you will be forgiven.
So, by trying to condemn you they are actually condemning themselves.
As Christians we are to love our neighbors as ourselves; we are not given authority to be the judge of people. So many Christians presume to know Gods heart and speak/act for Him which is it's own sin. They are today's Pharisees.
When someone is hammering you over the head with the bible - they are doing it wrong.