Low on cash and need to do laundry?
The poster of this one says to use pennies instead of quarters, noting that the hack sometimes works. There is a way to trick the machine, which is usually older than most of the people operating it. I would say that this hack is worth a shot, but the poster notes that it only works sometimes.
This means that you would be pushing your luck most of the time, but you might get lucky from time to time, with the occasional penny taking you far in life. If you cannot get this to work, the sink is always a great option.