When working at the trading floor at Cantor Fitzgerald one of the desk , Interest Rates Swaps (IRS), used to trade using hand movements. Have you ever seen the movie trading places? Well it was similar here. I was amazed at the energy and frantic hand movements when the brokers where trading. When you see pictures of the traders in the pit, here's what you're looking at:

Palms in , or "I'm a buyer"
Palms out,or "I'm a seller"
Hands away from body, with arms outstretched, fingers moving, or "Here's my price. (Prices 1-5 are quoted with vertically extended fingers, prices 6-9 are quoted with fingers horizontal, and a closed fist inditcates a zero price.)
Hands held near head,or "This is how many I want",

Of course, these brokers are all yelling, too. Do mistakes ever happen? Well, we're dealing with humans beings,rights? As long as the trade was booked correctly and matched that is all that counts in the end of the day. But it is fun to watch. Pure theatre.