It is not uncommon to hear credit cards referred to as "plastic money".
Vinals, Immaculada Barral
"The Cards As A Payment Method And As A Financial Service In Spain: The Responsibility System,"
ILSA Journal of International & Comparative Law: Vol. 14
, Article 3.
Available at: http://nsuworks.nova.edu/ilsajournal/vol14/iss3/3