It's a hoot!

[GRADMA at UVVM.UVIC.CA]

I've known and used this expression, as well as "What a hoot!", for as long as
I can remember, in both Ontario and B.C.,
and always assumed that it referred to a loud "hooting" laugh.`
The _Gage Canadian Dictionary_ (1997) has for "hoot" "5. Informal. something
causing laughter," and gives the etymology "ME hute(n); ? imitative." (Webster's
_New World..._ gives a similar etymology, with cognates in Swedish and
Norwegian, but doesn't give the "funny" definition.) Not a word about
Hutterites, of whom there is a large population in Alberta and Manitoba.

Barbara Harris