[Gnomes]

Tipping is a custom evolved from paying extra to ensure preferential service, better quality service, or a gratuity for good service.

With that, I tend to think tipping = borderline corruption. A co-worker of mine told me he went to vietnam. In the airport he is waiting in line for viet custom people to stamp passport and crap. He sees fellow canadian travelers in front of him taking a long time to "process". When it is finally his turn, he recalls his travel agent telling him to slip in a few bucks in his passport. Low and behold, he went through in less than 1 minute. Better preferential service and better quality service? Yes. Corruption? You be the judge.