Card Fart

When one's Debit / Credit / Whatever card misfires, fails or is abjectly declined for no apparent reason when being used to make a purchase in any PIN pad at a retail establishment.

I had just popped my chip card in the reader and IMMEDIATELY got a CARD DECLINED message. I know there's plenty of funds in there... so... it was just a Card Fart. Re-inserted it and all was fine.