Of course you can borrow money from a private person just as much as from a bank.
The tax requirements are these.
If your friend charges you interest, he must declare it as income on his tax return. However, you have no obligation to file any forms like a 1099 to report the interest income, since you are a private person.
The IRS also expects that financial transactions will occur in a businesslike manner, which includes charging interest. So if your friend does not charge interest, the IRS will still require that he report "imputed interest" income -- the interest income he would have received if he was lending the money in a businesslike manner.
However, your friend is unlikely to be audited, so if you aren't charged interest it probably doesn't matter (his risk).
Separately, there are many legal and social issues surrounding borrowing money from a friend, that we can't really go into here as we aren't attorneys or financial advisors. You will both need to know what you are doing, and probably want to prepare some kind of documents. (As a side note, some states have a cap on private loan interest to prevent loan sharking -- if he charges you too much, you can request a court judgment that voids the entire loan -- you get the keep the money and you don't have to repay the loan or the interest because it's an illegal loan. Hopefully that won't be an issue.)
