Re #6, #11:
I don't find it impossible to believe that a TV adaptation of Jane Austen, even one by the BBC, used a phrase that is obviously grossly anachronistic, just because they thought it would make modern audiences laugh. In my experience, period language, or at least language that doesn't jump out at you as modern, is often one of the most glaring things missing from historical costume dramas. (We've been re-watching Downton Abbey for the nth time, because for my mom it's only the second time, and it grates on me every time the characters say something is 'fun' as an adjective meaning entertaining, in contrast to a noun as in 'What fun!' I might be wrong, but I'm not convinced that was already widespread 100 years ago, especially in BE.)
It's true that Mrs. Bennet is a comic character, and it may be true that she's given to malapropisms, I can't remember. So in the TV version, she might have used 'to pot' in a sense similar to 'to bag' (= get by shooting), as in 'The hunter potted a hare.'
Still, the rest of the phrase as quoted with 'your can of it' (of what?) doesn't make sense to me at all, so perhaps lisa didn't quite hear it or remember it exactly as spoken. (We can now all go and see if we happen to have the DVD.)
And I'm skeptical that any of this has much bearing on the original discussion from 8 years ago, since even the songwriters admitted that they didn't really have a clear idea of what 'can the can' meant. I would have guessed maybe 'to can' in the sense of 'to sack' (= fire from a job) or just 'to end / stop sth.,' but I don't recognize 'can' as a noun meaning something like a jerk or an idiot.
Song lyrics don't always hold up to close scrutiny; sometimes they're just meant to sound funny, and that's all.