Apparently, if a user enters a negative amount in the "donate" thing, they actually TAKE money from you 
I noticed this when I got the message that I'd received a donation, and the amount was "-1000". I thought it was just a glitch, but then I checked my balance, and I was actually one minus a lot 
Then I thought that might have been a glitch too, so I went and clicked an adoptable, to see if I gained cash. I did. I was then on minus a lot minus ten 
..anyone know how to fix this?