forgive the correction, but having worked for them often, TIPS means TO INSURE PROPPER SERVICE, was the way I understood it. service could be both lousy AND prompt. and it is definitely not a city in China.
The phrase I've always heard is "Tipping is not a city in China."
What I'm not getting here is that If you tip at the end of your meal when paying your bill, how will that "insure prompt service"? Unless it is meant to insure prompt service the next time your in that restaurant? When I tip, it is to recognize a job well done, or maybe not well done, & the amount varies accordingly. I always tip, & when I get a waitperson that takes care of me, gets my order right, & doesn't hover, I tip a lot more!
