The Broadhurst Rule

Rule that is put into effect on certain social occasions that require multiple people to split a bill that could potentially cause complications. Someone must state ahead of time that the Broadhurst rule is "in effect" or else no one can be expected to observe it. When the rule is in effect, everyone attending the event must bring cash so no debit or credit cards have to be thrown onto the table in a massive, confusing pile. If someone forgets to observe the rule, they must pay for the whole bill with their card or leave right away at the beginning of the event.

You and 5 friends are going out to dinner to celebrate someone's birthday, ahead of time you state that the Broadhurst rule is "in effect" everyone except your friend Wayne brings cash to split the bill. Wayne now has to pay for the whole bill.