English
guinea pig night
From guinea pig + night, implying that the patrons are being used as guinea pigs to test the newly-assembled rides.
A compound of guinea pig + night
Proto-Indo-European *nókʷts ‘night’
Proto-Germanic *nahts ‘night’
Proto-West Germanic *naht ‘night’
Old English niht ‘night’
Middle English nighte
English night
Today it means
noun The opening night of a travelling funfair at a new location, sometimes accompanied by a discount or deal.
Language periods are conventional ranges, not dates for this word.
Etymograph / guinea pig night