I did it. You take 2tbs of fresh baking soda and your first morning pee and combine the two. If it fizzes it's a boy if it doesn't fizz it's a girl. The science behind it is that if your having a boy the acidic level of your pee should be higher than if it's a girl. I read some blogs where there was some accuracy however some had it be inaccurate so it's clearly not 100% or they did it wrong somehow? I did it, however I don't find out for another 3weeks whether it is correct! :)
Nothing is 100%. It's all 50/50 just for fun... I mean even ultrasounds can be wrong haha!!