This is a misnomer. Here is an extract from Wikipedia that says that it is a myth:-
Shit is an English word that is usually considered vulgar and profane in Modern English. As a noun it refers to fecal matter (excrement) and as a verb it means to defecate or defecate in; in the plural ("the shits") it means diarrhea. Shite is also a common variant in British English and Irish English. As a slang term, it has many meanings, including: nonsense, foolishness, something of little value or quality, trivial and usually boastful or inaccurate talk, or a contemptible person. It may also be used as an expression of annoyance, surprise, or anger, and has other usages as well.
The word is likely derived from Old English, having the nouns scite (dung, attested only in place names) and scitte (diarrhoea), and the verb scītan (to defecate, attested only in bescītan, to cover with excrement); eventually it morphed into Middle English schītte (excrement), schyt (diarrhoea) and shiten (to defecate), and it is virtually certain that it was used in some form by preliterate Germanic tribes at the time of the Roman Empire. The word may be further traced to Proto-Germanic *skit-, and ultimately to Proto-Indo-European *skheid-. The word has several cognates in modern Germanic languages, such as German Scheiße, Dutch schijt, Swedish skit, Icelandic skítur, Norwegian skitt etc. Ancient Greek had 'skor' (gen. 'skatos' hence 'scato-'), from Proto-Indo-European *sker-, which is likely unrelated.
A popular belief is that the word shit originated as an acronym for "Ship High In Transit", referring to the apparent need to stow manure well above the water line when transporting it by ship. This has been shown to be a myth.
From: Sunil Kumar Vohra <email@example.com>
To: Keralites <Keralites@YahooGroups.com>
Sent: Monday, 13 February 2012 10:48 PM
Subject: [www.keralites.net] How Shit got its name
... it adds to my knowledge ...*Manure ... *An interesting fact*
*Manure *: In the 16th and 17th centuries, everything had to be transported by ship and it was also before the invention of commercial fertilizers, so large shipments of manure were quite common.
*It was shipped dry, because in dry form it weighed a lot less than when wet, but once water (at sea) hit it, not only did it become heavier, but the process of fermentation began again, of which a by product is methane gas of course. As the stuff was stored below decks in bundles you can see what could (and did) happen.Methane began to build up below decks and the first time someone came below at night with a lantern, BOOM!*Several ships were destroyed in this manner before it was determined just what was happening.
*After that, the bundles of manure were always stamped with the instruction,' Stow high in transit ' on them, which meant for the sailors to stow it high enough off the lower decks so that any water that came into the hold would not touch this volatile cargo and start the production of methane.*
*Thus evolved the term ' S.H.I.T ', (Stow High In Transit) which has come down through the centuries, and is in use to this very day. *Col S.K Vohra
Army Medical Corps