Change We Can Believe In (1980s Edition)

In introducing the concept of fractional-reserve banking to my students today, I said that a bank which held reserves equal to its deposits wouldn't be profitable.  I'd forgotten this classic example of another way banks could make money:



That was even funnier back in the late 1980s when TV viewers were inundated with the annoying Citibank ads being parodied. Also see this follow-up.