Answer: When you stand in a line behind two of your friends, you will be the third person in line. This is because when you are standing behind two people, they would be considered the first and second person in line, making you the next person which is the third. This concept is based on the order of people in line starting from the front. It is a simple counting principle where the person at the front is counted as first, the person behind them is second, and the following person is third in line.