Few sentences from a sketch show - what do they mean?

I was watching a sketch show ‘Watson and Oliver’ (episode 1) and there were a couple of sentences I couldn’t make out even though I had subtitles.

‘Mind you, she’s a wicked old bag is that Margaret Drummond, and you’re not safe from her fishwife’s tongue. She’s called you common on many an occasion, and no mistake!’
There I don’t understand the ending of the first sentence and, actually, anything in the second at all.

‘But hark at me going on at you. That’s men!’
I think I understand ‘hark at’ but, as the whole, it’s a bit vague for me.

And what could mean ‘slops duty’ if it is used by a prisoner?

Oh, and one more question if someone happened to watch this episode - how difficult for you was it to hear every individual word in the first sketch (from which I took sentences above) and the one played in a kind of restaurant/bar ? For me it was like verging on the impossible to make out what they were saying… well, and still is :confused:

Thanks for help!

From various sources around the web:
“no mistake” - make no mistake about it.

“common” - I suppose in this case it means plain, ordinary.

“fishwife” - A woman regarded as coarse and shrewishly abusive.

“hark at me” - said to someone who has just accused you of something that you think they are guilty of themselves.

As for “slops duty”, I’m not sure, but wikipedia says “slopping out” is “the emptying of buckets of human waste when the cells are unlocked in prisons in the morning.”