My big win at the airport slots was $15 from one of the machines at the old Hughes terminal. I was waiting to go back home many years ago and had 1 1/2 hours to kill so I decided to play a nickel slot. In the row of about 6 slots one was buzzing and whirring so I decided to stay away from it. After playing for a little while and continuing to lose (of course) I decided to play the buzzing machine. It was a 3 coin machine and when I put one coin in it gave me credit for two. When I put two coins in it gave me credit for three. There was no big bonus for more coins and I finally figured out that if I put in two coins it was giving me a 50% bonus whereas if I put in one coin it was giving me a 100% bonus. I played that machine for the hour and a half and came away $15 ahead and I could barely lift my arm it was so sore.