What “Crosses” means
Crosses means trouble, misfortune or bad luck. On its own, "Crosses!" is an exclamation of dismay when something goes wrong.
Examples
Crosses! Mi lose mi phone again.
What bad luck! I lost my phone again.
Mi nuh want no crosses inna mi life.
I don't want any trouble in my life.
How to use it
Everyday word. As an exclamation it's mild and fine around anyone.