A tip is defined as a bonus, a little extra, a bit extra, a present, a gift, a reward or an inducement. About 25 years ago I lived in the United States for two years. In those days, if you went to a restaurant where you dined, the unspoken role was that you left a tip of at least 10 per cent of the bill.
At that time, wait staff at restaurants were paid below the minimum wage at the time which was about $5.50 an hour, and they were expected to make up the difference in tips.
