You do need pee from the same sex as you they can tell easily.

Heat it up, wear whitey tidey underwear, (which I hate,) and snug the pee on your taint.

Last time I did that, the test people said it was a little hotter than it should be, I said it's hot out and I walked here.

Best though, if you quit for several days first, drink lots and lots of water to dilute your piss, then take a few vitamins to add colour to your pee. It works.