Maybe if said woman has a gun to his head.

Yes. I think a man has every right to protect himself against a woman if she is physically abusing/attacking him.

Yes, when she throws the first blow. My grandfather said "If you're big enough to throw a lick, you're big enough to take one". Everyone needs to keep their hands to themselves.

Absolutely

only when he doesn't get a sammich.

Self defense

There are an infinite number of such instances. Would you care for an example?

I think it's okay when it's in self defense and the crime equals the punishment. Iykwim

If that woman is running at him with a knife or is going to try and hurt him physically in some other way, then sure, it's acceptable.

Yes

Yes - if she hits him. Men aren't punching bags and I for one do not expect a bloke to stand there and get beat on by a woman just because she is a woman

The only one would be in self defense

Its acceptable if woman deserved it otherwise its sexist not to hit a woman

No man should ever hit a woman, unless defending his life.

HELLLLLLLL NOOOOO!!!!!

We are all one ,there is no weaker sex so it's fine in my book

Not that I can think of.

If it’s the only way to stop her from physically harming him.

Is there any instance when it's acceptable for a man to hit a dog?

No, nor a woman hitting a man either.

what if shes stabbing him with 2 knives and kicking him?..

Yes. Right before she stabs or shoots me. No other reason.