In all seriousness, how do you borrow that amount of money?
The US Treasury issues bonds
I think it is mostly domestic and foreign private investors, with sovereign (foreign) investors also contributing.
What do you have to do to convince people to lend it to you?
Right now it seems sufficient to offer to pay a yield to maturity of about 3% for ten years, or about 3.7% for 30 years, in US dollars. In other words, compared to much of recent history (last few decades) not very much at all.
If that seems strange--say, because the supply of US government debt is so much larger today than over that recent history, so how come people buy it for what is to all intents a higher price--it's because their willingness to hold almost anything else has declined to a great extent. Thus,
despite the global pool of savings (the potential demand pool) being smaller, and
despite the supply of US government bonds being bigger, investor
preferences for US government debt over almost everything else they could do with savings has rocketed to such an extent that they will accept a
lower reward for lending
more to the US government
today than the reward they would accept to lend
less to it
before.
I know that people sometimes talk about the government "printing money", but I know it doesn't really work that way.
It does sometimes. It depends on who is the buyer of newly issued bonds. If global investors, as above, lend to the US government then it is not "printing money" because no increase in the US dollar monetary base ever took place. The government borrowed more money from people, but it was money they had already, and which they diverted from whatever it was saved/invested in before into newly issued US government bonds.
If, however, the
Federal Reserve "bought" newly issued bonds, then (unless the Fed liquidated some of the couple of trillion third-party assets it currently owns which is not going to happen) the Fed needs to "print" new money to do that. What happpens is that the Fed credits the US government with the sale proceeds of the new bonds. If that sounds incestuous that is because it is of course. Effectively it is the same as the government rolling the printing presses itself. It's just that the accounting and the institutions involved are different (EG the Federal Reserve is not under the control of the executive branch of the US government except at an arms-length level, whereby the President appoints the chairman of the Fed for fixed terms, and the Secretary of the Treasury generally consults with the Fed chairman and does things that the Fed chairman tends to agree with)
I suppose the government could loan money from the Fed to member banks, who could then turn around and invest that money in Treasury Bills, giving them a low risk investment, but wouldn't that be just like, well, printing money, and wouldn't that make inflation skyrocket?
The government can't technically lend money without first getting it from somewhere. It is the Fed which "creates money". The government could do it if it raised taxes or borrowed it from somewhere else or sold state-owned assets, but those things don't create more money, they just shift it around.
As for inflation skyrocketing, Austrian economics aside, an increase in monetary base should cause an increase in price levels
all else remaining unchanged. But there is a huge amount of "all else" that would have to remain unchanged. (The velocity of money, sometimes known as "money demand" for one). Moreover, it should increase price levels
relative to what would happen otherwise. If what would happen otherwise (due to a massive slump in real final sales in the economy, for instance) is the price level fallling 5%, then monetary base expansion that
offsets this would generally be viewed as a desirable policy.