can you swallow a long string so that it comes out your anus while the train of it is still contained by your mouth?

As others pointed out, the digestive cycle spans over more than a day and if your string is made of a wonder substance which resists digestion while still allowing it to be a flexible string, you might succeed.! Only you might need to swallow the string slowly, read aloud, an inch every few minutes or so.
In yoga, there is a process of swallowing a string and getting it out through one of the nostrils. It's expected for cleansing the nasal passages.
i would envision that your stomach acid would disolve string.
u cant do that. see in your mind`s eye urself walking with a string out of ur mouth. plus its impossible since tart in ur stomach would probably dissolve the string even in the past its reach ur rectum. if u hack it, by miracle, take a picture of it and another picture of u holding both ends and verbs. post it in the internet. it might be amusing. ps: convey a copy to my mail, please. ^__^ hold a nice 'try'.
this is not possible for anyone because moral fibre has created our gastrointestinal tract something resembling this:
when we eat something it go to stomach .in stomach it take minimum 4 hrs.to digest food.then it go to small intestine ,then colons(large intestine)then comes to anus.for this complete process it takes minimum 20-24 hrs.
so, your imagin story is unworkable as far as our nature have concerned.
You do that, then you'll be the first individual to bodygloss like dental floss.
try and communicate what happens..
appropriate luck