Means extra money, a little bonus, or unexpected profit that drops in your lap. Could be a cheeky refund, a surprise commission, or finding a tenner in an old jacket. Often said as “a nice bit of bunce”. It’s not life changing cash, just enough to make you feel smug all day.
"Checked my bank app on the bus and there’s a random refund from the leccy company. Nice bit of bunce, mate. Straight to the chippy for a celebratory scran."