It is expected people will pay for themselves.
Tina is having a girls night out with her friend at the bar.
Tina wants to avoid spending too much money at the bar.
Tina sticks to cheaper drinks and only orders a few of them.
Tina orders a bunch of drinks and puts it on her friend's tab.
Tina's friend has a great time out with her and can't wait to do it again in the future.
The friend's night is ruined when she is stuck with a much higher bill.