Me to other woman at park with fluffy dog similar to mine- ‘aaah it’s so cute!’ Woman- ‘ACTUALLY he’s a boy. What’s yours?’
Me ‘um... female. Ok, well, must find the bin! ’ (Waves with bag of shit in hand)
Some things to say back I thought of later:
‘Surely it’s a man not a boy, he’s got a bit of grey in the muzzle!’
‘No idea what the sex is, never checked’
‘Don’t worry I’m not going to try to get them to breed here in the park’
Seriously though unless you are actively trying to breed dogs the sex is utterly irrelevant and I hate the fact that gender roles are so endemic that people try to push them on animals to the point that they get ANNOYED if you ‘misgender’ their pets.