Remember in Hero when everyone was writing 天下 ("[All that is] under heaven") all over the place, and it meant that it was OK to unify China by any means necessary? There are actually a bunch of four-character compounds that start with 天下, too. Here are a few:

天下太平
ten ka tai hei
heaven under broad peace

You can also write this 天下泰平, if for example you get paid by the brushstroke. It describes what's supposed to happen if everyone -- but especially the Emperor -- is sufficiently virtuous, but nowadays you can also use it to just describe general peace and happiness.

天下無双
ten ka mu sou
heaven under no twin

Hey, it's the same 無双 as in 古今無双! And this compound means basically the same thing.

天下一品
ten ka ip pin
heaven under one item

Something so great, nothing else under heaven compares to it. This one, people actually use, but they seem to mostly use it to describe food.