ISHT

[FRITZ JUENGLING]

How about those folks from Minnesota who have been saying 'ish' for generations?  They won't be able to say it in nice company anymore, will they?

The Minnesota 'ish' is not the same as the one being discussed, but can be used as both an adjective and exclamation, altho both indicate disagreeableness.
Fritz

and. as larry horn is about to observe in the very next ADS posting,
his yale students have been reporting (spoken) slang "ish" for "shit"
for some years.  (i agree with larry that this is probably a
cluster-simplified version of "isht".)  quite
probably taboo avoidance, but of the everybody-gets-it sort, as with
"freakin'" and "friggin'" etc. for "fuckin'" (see The F-Word for plenty
of examples).

some of the users might not even see the "shit" in "ish".

arnold