So, Wednesday night is bridge practice night (yes, I am getting better at it, thanks for asking); table money is £6. Yesterday morning I had no cash in my purse, so I took £20 out of the cashpoint before work. So in my purse, I had two crispy ten pound notes.
Bridge arrives; I buy a round of drinks at the bar, which amounts to £8.25, knowing that I'll be able to pay my table money with the other tenner.
Bridge finishes - it's time to pay. I reach for my purse, and open it to find...two ten pound notes.