punching the back of someone's seat. Maybe with some airlines it works.

Usually, I see it happen by changing seats with someone at the flight attendant's request, maybe you get something spilled on you by accident, these types of things where a passenger is inconvenienced for some reason usually result in a free drink.

So either, she is lying about the free drink and attendant telling her she would be escorted off the plane or she isn't telling the complete truth of what happened if in fact the flight attendant gave the guy a drink and told her she would be escorted off.