No Money in Those Trust Funds

Again and again I see the contents of the Medicare and Social Security Trust Funds referred to as "money" or "cash." Here, for example. Another one here, for example:

Social Security, financed through payroll taxes, has enough money in its trust fund to pay full benefits through 2037, according to its 2010 trustees report.

Good grief. There is no money in these trust funds. There is no cash in these trust funds. The trust funds contain special government bonds, not money to pay out to beneficiaries. All the cash that has been collected through Social Security and Medicare taxes has been spent already. To get the money to pay beneficiaries, the government will need to use taxes, borrowing, or printing.