The Double Duffy is used in staff meetings when frustration mounts to the point that you cannot take it anymore. It is usually directed at the person running the meeting, but can also be directed at colleagues. This will usually either end the meeting or move it right along. The double Duffy consists of two middle fingers being directed from the same person.
Can you believe what the boss was griping about in that meeting? I wanted to give him a double Duffy.