trying to find out what the heck is Upside Down XD I found the 2008 trailer for a movie that looks good.

It's this wacky parallel dimension in Stranger Things, is that what you found? :)

ahhh I know what it is hahaha.
But no, I saw a movie where there are two worlds turned upside down and two people fall in love, but there is a kind of racism because those below are poor, is what I understood from the trailer.