It ... sounds pretty self-explanatory to me ....

[Pixelated]

A younger customer came through my register today (then again, in my eyes, everybody is 'younger' ). I ring through his few items and total it up. He inserts his debit card, stares at the screen, and then looks up at me.

Customer: "What's 'cash-back'?"

Me:

[Ironclad Alibi]

Oh great! another staple (cash) from my long life is no longer recognized by the youngest generation.