oh shit - some etymology
The verb shit started out in Old English as shite (from *scitan, where sc- is pronounced sh-). It probably attained its current form by influence of shite's past participle, shitten. It goes back to the proto-Germanic root *skit-, which gave birth to German scheissen, Dutch schijten, Swedish skita, and Danish skide as well. *Skit- derives from the Indo-European root *skei- "split, divide, separate" (which also gave English schism and schist). The sense here is of "separating" excrement from the body. This word is NOT an acronym formed from ship high in transit.
found here