Previous work has demonstrated that unacquainted participants in an experimental, restaurant‐like setting consume more when they know in advance that the bill will be split evenly rather than paid according to individual consumption. Real life, however, often differs from these experimental settings in two important ways. First, unlike random groups of participants, diners who eat together are frequently friends or colleagues. Second, payment method (even vs. individual payment) is usually unknown (i.e. uncertain) at the time people place their orders, and is determined when the check arrives. The current research tests the ecological validity of the association between consumption amount and payment method. Study 1 was conducted in a natural setting with organic groups of diners. Some were asked to state their desired payment method before ordering (Certain condition); others did so only after asking for the check (Uncertain condition). In both conditions, even payment (as opposed to individual payment) was associated with greater consumption amount. However, overall, consumption amount was lower among diners in the Uncertain condition than among those in the Certain condition. Study 2 presents a controlled follow‐up experiment showing that eliminating diners' prior expectations regarding the payment method—by informing them that the payment method will be randomly determined after the consumption decision—eliminates the relationship between payment method and consumption amount. This study further indicates that when diners are uncertain what the payment method will be, even bill‐splitting has negative implications for their subsequent social interactions, expressed in retribution tendencies. Copyright © 2016 John Wiley & Sons, Ltd.