Is the following sentence grammatically correct?
I do do shopping on weekends.
The negative of this statement would have been:
I don't do shopping on weekdays.
But a friend of mine said this is incorrect grammatically. Why?
The simple present verb is shop.
I shop on weekends.
But we can also use the nominal -ing form to refer to the act as a common task or a regular chore, in which case we use the verb do:
This weekend, I have do some shopping for a new car, and I also have to do some tidying up in preparation for guests who are coming to visit.
This Saturday is going to be a busy day. I have to do the shopping, the washing (i.e. the laundry), then some pet-sitting, and finally some plumbing.
Over the centuries, some of these -ing forms can become bona-fide nouns from common use.
The phrase do do the shopping is an example of the above coupled with emphatic do. Emphatic do reinforces or underscores the assertion. Here is emphatic do in action:
I do believe in spooks! I do believe in spooks. I do. I do. I do. I do. I do.
Paraphrase: I do indeed believe in spooks! I certainly do.
You would need a context to use emphatic do with do the shopping.
To say "I do do the shopping on weekends" emphasizes the truth of the particular assertion. Why would you want or need to emphasize it? Perhaps to counter someone who says something like the following to you:
Why can't you come to the beach with us this Saturday?
To which you reply:
I do the shopping on Saturday.
To which the first person retorts:
Nobody shops on Saturday, fool! I never do the shopping on Saturday.
To which you might reply:
Well, I do do shopping on Saturday.
This is the contrast that @TRomano is referring to
Some people don't do their shopping on weekends, and some people do do their shopping on weekends.
Instead of
I don't do my shopping on weekends.
vs
I do my shopping on weekends.
You'd only say...
). Can you explain it a bit more verbosely?