You go out to eat with a friend. You sit down at a restuarant. After you both enjoy the meal, the waiter puts down the bill. Instantly, both of you pounce on the bill. You grab it and refuse to let your friend pay. He argues that it is he that should pay and that it is not proper for you to pay. You both go back and forth, wrestling with the bill, trying to rip it out of the other person's hand. After a lot of negotiating and making the other person guilty and protests, finally one of you resigns to letting the other person pay. What is this called?