A close friend (or a mere acquaintance) of yours approaches you. States that he/she is badly in need of some money. And you oblige. In the back of your mind you know that the money would be returned to you, but there's no guarantee.
For what causes would you oblige? Would you cough up a small amount for a start-up business? Max how much would you cough up?
(I know the extent of amount would vary depending on the purpose. Hence, feel free to cite as many examples as you want.)