Shagoween means is a slang term for Halloween in the UK ( England wales Scotland and Ireland ) they have used this term just to be different from the rest of the world.
A: hey man shagoweens coming up what you gonna dress as?
B: I completely forgot shagoween was this month. We should go as planes and John can go as the twin towers.
A: Yo that’s a sick idea, btw Emma invited you to her shagoween party you gonna go?