When did films become movies?
...and 'can I do' is so vague and suggestive that the mind might boggle at the options.
'Doing a donut' is maybe something a stunt driver might undertake, for example...
'Can I get' really annoys me. I wish for a shop worker who gently replies, 'No, it's my job to get those for customers. Would you like one?'
I was brought up to ask 'Please may I have...' which is much more polite.
There's certainly a big gap between doing and having and doing a coffe and donut makes no contextual sense