In the 16th and 17th centuries, everything had to be
transported by ship and it was also before commercial
fertilizer's invention, so large shipments of manure
were common.

It was shipped dry, because in dry form it weighed a
lot less than when wet, but once water (at sea) hit
it, it not only became heavier, but the process of
fermentation began again, of which a by product is
methane gas. 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,
BOOOOM! 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 term "Ship 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 " , (Ship High In
Transport) which has come down through the centuries
and is in use to this very day. You probably did not
know the true history of this word. Neither did I. I
had always thought it was a golf term!

and here I thought S.H.I.T. stood for "Sure Happy t
Its Thursday"!!