I'm not sure where you are from but a 20% tip is expected in the US. Servers basically only make money from tips as the hourly wage is just over $2 an hour. So the tip should have been $18.50, not $8. You basically insulted and stiffed the server. If there was a problem with the food or service you should have brought it up to the manager, not just undertip the server and leave.
We've eaten here plenty of times and I never heard anything like that! I often give the change so the wait person has even dollar amount. I'm assuming you added to the 8 dollars for a nice tip!
So was your tip $8? Roughly 8%? Just to be clear. And no she would never have to pay more than your food was... which I'm still unclear about on this question.
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