Here's some English drinking lore.
Can you see the difference between these two glasses?
No, neither could I.
But the one on the left has a bit of a shoulder to it , which makes it a "gentleman's glass", whereas the other has a smoother contour, which makes it a "lady's glass".
Ailz (who used to be a pub landlady) pointed this out in the nick of time and saved me from committing a terrible social blunder.