Hey Jack Campin! It's a month later, and I'm just reading your post.

Thanks for your warm welcome.

I very much appreciate it-then and now.

**

As to your question about the phrase "Do you know Giacomo?". Hmmm, that sounds a little like one of them there "rhyming expressions" that are the focus of this thread:
thread.cfm?threadid=104417&messages=23 "Folklore: Puddin Tane & Other Rhyming Sayings"

[That is, assuming that the name Giacomo is pronounced like Jockomo which means that it rhymes with the English word know.

And, isn't the Italian name "Giacomo" the same as the English name "Jack"?

So then, Jack, I'm wondering if the saying "Do you know Giacomo?" [which I've never heard of or read before reading your post] could be the source of the colloquial expression "He don't know Jack". But the sentence "He don't know Jack" actually ends with the word "sh*t", though that last word is not stated in what some people call "polite" society. But though it's silent, it's still understood.

So if you want to say that a person doesn't know anything at all about anything, then you'd say "He don't know Jack".

But given that colloquial expression's definition, I guess it means that "Do you know Giacomo?" and "He don't know Jack" probably don't have the same etymological roots 'cause I'm assuming that "Giacomo" is a man's name, and I think that "Giacomo means "Jack" though, on second or third thought "Giacomo" might mean "James" or "Jacob" and if so my theory about any connection what so between those two expressions is totally wacked.

Do you get my drift?

No?

Well that's okay.

Sometimes I don't know Jack.

But, any ways Jack Campin, I'm glad to have met you over these internets.

:o)

Post script:

Wanna read a witty entry about the meaning of "Jack Sh*t?
Click here.