Reliable self-delusion
Debit card transactions aren't real money; at least, so I keep telling myself. If reliabilists can say that sense data acquired with reliable methods constitutes "justified knowledge", then I think I'm reliably justified in knowing that inscribing your name in a signatory flourish at the bottom of a receipt for £23.99 isn't actually real money, since my reliable senses tell me that £20 notes are a lot bigger and more purple, and £3.99 is far more coin-y.
It was for a book called "Knowledge", and therein lies the irony.