A coded phrase used to let a friend know that they their butt crack is clearly defined by the garment they are wearing on their ass (e.g. pants, skirt, bathing suit, etc.), without letting others know the message. The association being that a wedgie resembles a card swiping machine that one would use to pay with a credit or debit card.
As Gabrielle stepped out of the pool, I noticed she had a severe wedgie. So to save my friend any embarrassment, I quickly yelled " Hey Gabrielle, credit or debit?" whereas she responded with a quick picking of the wedge.