"The Upside-Down World Paradox"

Given my fondness for paradox, just linking today to this quirky, fun little (non-mathematical, but logical) post about the 'upside-down world game' (an offshoot of 'the liar paradox'):

http://m-phi.blogspot.com/2014/10/the-upside-down-world-paradox.html

The blogger's seven-year-old daughter enjoys the game in the post, so if you have young kids maybe they will as well.