Merriam-Webster wrote
Quote:Main Entry: Si·wash
Pronunciation: 'sI-"wosh, -"wäsh
Function: noun
Etymology: Siwash, fictional college in stories by George Fitch died 1915 American author
Date: 1936
: a small usually inland college that is notably provincial in outlook <cheer for dear old Siwash>
So I imagine something that has to do with that novel, hey what do I know, I'm juast a swede using the M-W for fun!