The other problem I see with this is: you have no one in the real world who can lend you $40 for 3 days and you have to resort to a forum and hope you can borrow it from a stranger? It doesn't smell right, and if it doesn't smell right, no one is going to lend it to you.

On the other hand, assuming your story is true and you're not trying to scam anyone, paying 20% for 3 days of borrowing is going to make your poor financial situation even worse.