stupid thing is that if you are a bloke - as I am - you know full well that there is long-established unwritten rules when using toilets. It's this:
- don't look at anyone else - even if you know them
- don't engage with them in any way shape or fashion - even if you know them
- do your business quickly, quietly and get out!
If you're in a men's toilet and a woman (or someone who looks like a woman) enters then 99% of the time you won't notice - because of rule 1 above.
On the off chance that you do notice the most likely outcome is that they will simply be ignored. There is a small chance that the woman might get a shout out along the lines of 'alright love, the women's is next door!'
The chances of men, mocking, coming on to or even attacking said woman are remote in the extreme.