Ah yes - thats very correct according to recent folklore.
But think about it for a moment - why has the haggis never been caught ?
I always understood that you could catch a haggis by waiting at the
bottom of a likely slope with a set of bagpipes at the ready. You
wait quietly until you see a haggis traversing the slope. Then you
play the bagpipes, which gives the poor creature sucha fright that it
turns and tries to run the other way. since it then has its long
leg(s) higher up than the short one(s), it loses its balance and
tumbles down the hill into your waiting arms (or a net, if you've had
the forethought to bring one with you).
By the way I'm not sure that the plural of haggis can be haggi. The
-i ending is OK for words like cactus and discus. Haggis belongs to
the Latin 3rd declension (like axis and oasis). Its plural therefore
must be hagges. Sorry to be pedantic, but a serious subject like this
deserves appropriate treatment.
Haggis pre-dates the Roman invasion, so cannot have a Latin root.. The word is actually of Gaelic origin.
I believe that 'haggises', although unweildy, is correct. Some simply say 'haggis'.