My Dad could usually contrive to go astern when going about; he would invariably worry so much about the boom that he would forget which item to pull, and which way. He would end up in stays with the rudder on one tack, the jib sheeted home on the other, the mainsail flapping and the dinghy going slowly in reverse. OK, not "Full Astern", but good enough to cause chaos in any bunch of racers rounding a marker.

There is a story of an RAF Bomb Aimer, whose instructions to the pilot went roughly, "Left...left...left a bit...no, right...no, we're over, come back a bit, come back a bit...". It was just as well that Lancasters didn't have reverse thrust.

Nicole, thanks for the link. 14000 gigatons of trapped methane is an awful lot of discarded refridgerators or flatulent cetaceans (or degeneration of Cretaceous sapropelic sediments).