ALRIGHT! heres how this will work. You will need a friend for this, 50 dollars each and a small box
1- You and your friend both put 20 dollars into that box
2- You sell your friend the box for 30$
3- You gain 30 minus 20 from selling the box and he gains 40 minus the 30 he bought the box for!
4- YOU BOTH GAIN 10$ !!!!!!