Not the full shilling British informal
Stupid or crazy
He is definitely not the full shilling when wearing a thick coat in this sultry weather.
You are not the full shilling if you think that this app will pay you money at such an interest rate.
Extremely stupid
Very stupid, or silly
A very offensive term used to describe an upper-class British man who is stupid or inexperienced
If you're off your trolley, your ideas or behaviour are crazy or insane.
To keep optimistic or have hope that something positive will occur and simultaneously prepare for a negative outcome
All I can do is hoping for the best and preparing for the worst.