As far as I can tell, this snowclone originated with dialogue in The Wizard of Oz (1939): “Lions and tigers and bears, oh my!“
The variables may be plural or singular, count or non-count:
filling and sanding and brickwork oh my!
comments and trackbacks and thumbnails oh my!
mugging and sugging and pugging oh my!
servals and binturongs and coatimundis oh my!
goblins and wizards and orcs oh my!
turtles and lizards and snakes oh my!
goblins and witches and halfwits oh my!
lions and tigers and misogynists oh my!
trojans and dialers and spies oh my!
night elves and taurens and gnomes oh my!
kiddies and kiddies and kiddies oh my!
ilyrians and romans and greeks oh my!
ninjas and ninjas and ninjas oh my!
lions and hyenas and pumbaa oh my!
ligers and tigons and pizzlies oh my!
turtles and rabbits and moles oh my!
To my ear, there is a stress limitation on the variables; that is, the stress pattern of the snowclone must match “LIons and TIgers and BEARS, oh MY!” The “hyenas” of “LIons and hyEnas and PUMbaa oh MY!” would then violate this constraint. To my eye, however, the constraint is much laxer, so I’d let it pass in writing. It does seem that for other people, “oh my!” is a strong enough this-is-a-snowclone signal to give them greater flexibility on the variables. “Cursors, and Text, and HTML…. Oh My!” is awkward no matter what, though.
This snowclone was one of my [Erin's] original inspirations for the Snowclones Database. I discussed it with some Livejournal friends here.