When I was on a plane yesterday, I was browsing through a catalogue that sells mugs with a clock on it. I was thinking who will want such a mug...at least not Chinese. Clocks are very bad gifts for Chinese, because it means "I'm sending you to hell" or "I'm putting an end to your life."
This is a very important etiquette for those who do business with Chinese. If you ever send your business partner or a friend a clock, your relationship will probably just end right there.