It sounds fishy, and it sounds like you are twisting the facts to try to get around the tax laws.
How does "Help South America" know that a particular donor is a friend of yours? If they normally require volunteers to pay for their own food and housing, with no reimbursement, what makes them decide to cover that cost for a particular volunteer? It sure sounds like a donation directed to a particular individual. It doesn't pass the "smell test." I don't think your friend could claim a tax deduction for the donation.
However, a charitable organization can pay your travel expenses, including lodging and meals, when you are performing services for the organization. If they choose to do that, it's not a gift to you, and it's not income that you have to report. But the question here is what is making them decide to pay travel expenses for one particular volunteer, when their normal policy is not to pay or reimburse the expenses.
So the bottom line, as I see it, is that you don't have to report anything, but your friend cannot deduct the donation.
It's essentially a gift to you from your friend, passed through an organization. Gifts that you receive are not taxable to you, and you do not report them anywhere. Gift tax is the responsibility of the giver, not the recipient. But if someone gives you gifts totaling less than $16,000 for the year, they do not have to file a gift tax return or pay any gift tax.
