It's usually used when you are surprised
to learn something. Other uses are to add how serious
you are being about something. The last and most obscure usage
is to explain the status of a couple. They are "For Realsies" if they are officially
"Koalas aren't bears they're marsupials!"
Usage 2:(add sincerity)
"I have always dreamed of being a plumber"
"Are you serious?"
"Did you here Jack
and Jill are for realsies now?"