Here is a funny trick I played on a friend of mine at a bingo hall. He wanted one number for a £1000, so I looked at his card and saw that he needed number 46. Of course what I did then, was cross out number 46 on my bingo card, wait for someone else to shout House. After all the sound of disappointment coming from my friend had died down, I then asked him what number he needed, making a point of showing him my card to show that I was miles away. You can not imagine how white my friend looked.