Pregnant women can pee in a policemans helmet,if desperate
Incredibly, this is actually a myth, it has never been a law and there are a lot of (fairly obvious) reasons for it.
It seems to have come about because officers are "advised" to use "discretionary" powers and not to fine/arrest pregnant women from urinating in public.
This seems to be an eminently sensible idea (as long as it's not in the middle of a shop/pavement).
As things will, with half truths and whispers this became a story that a pregnant woman could urinate "anywhere she liked", and so offices/banks etc, "by law" people will claim, have to let her use their toilets (again, untrue, although it could be helpful, and somewhat less messy to do so).
The "allowed to pee anywhere...." Idea was passed into public lore, with a few asking if "anywhere" were truly without exception, the humorist suggesting that this would then include a policemans helmet, which, if you take "anywhere" as an absolute, it would, and so the myth was born.
You can't, you have never been able to, it's not a law.
You'll still get told it is though.