Usually you hear it with a relative clause introducer-- "eating something [which, that] I don't know what it is"---- IIRC I've mainly heard it from (usually) Jewish comedians poking fun at their elders who were Yiddish speakers with poor English..... But AFAIK none of the languages that underlie or influenced Yiddish required a resumptive pronoun in the rel. clause. Maybe standard Engl. speakers picked it up and use it because they think it funny ????

ObConlang-- it's a perfectly good Kash construction :-)))

On Tuesday, March 25, 2014 10:29 AM, Jim Henry <[log in to unmask]> wrote:
On Tue, Mar 25, 2014 at 5:35 AM, Leonardo Castro <[log in to unmask]> wrote:

> What about "...what it is."?

"...eating something, I don't know what it is" is acceptable in some
dialects, but not in formal American (or I suppose British) English.

Jim Henry