On your uppers
Definition 1 of 1
Pro Tip 1/3British Origin
The phrase is mainly used in the UK, so it may not be well understood elsewhere. 
When I moved to America, nobody understood when I said I was on my uppers.
Pro Tip 2/3Figurative Use
'On your uppers' is a metaphor related to worn-out shoe soles, meaning you've hit a low point. 
Without a penny to his name, he was truly on his uppers.
Pro Tip 3/3Informal Context
The expression is casual and typically used in informal conversations or writing. 
I can't join you for dinner, I'm on my uppers until payday.