kafufnik - A tourist's rude name for money from other countries that's

A tourist's rude name for money from other countries that's not American; usually from places that look like they're about to fall apart.

"Kafufnik is just a fancy word for broke money.", Tom, in Mexico.

I tried to pay with kafufnik, and the guy said, 'You're trying to buy a pizza with a joke.'", Sarah, in Italy.

Kafufnik is like trying to pay with a coupon in a place that doesn't take coupons.", Alex, in Brazil.