A person who is Scirish is a person whose nationalities are both Irish and Scottish. In case you don't understand, it's a combo of Scottish and Irish.
Person: Hey, I'm Irish!
Dude: No WAI! I am Irish too!
Person: I'm also Scottish!
Dude: No WAI! I'm Scottish too!
Person: We're Scirish!
Dude: The fuck?
A person that are irish and scottish
"Hey where are your origins from?"
"Irish and Scotland"