Analysis of information sources in references of the Wikipedia article "波兰球" in Chinese language version.
In the very first polandball comics made on Krautchan in 2009, FALCO (the person who invented polandball) drew Poland's colors upside down. It's not known whether or not this was done by accident, or if he did it intentionally to piss off the Polish nationalists on that image board. Either way it worked, the Poles got angry about it, everyone else thought it was funny, and it stuck. That is the real reason why Poland is upside down.
In the very first polandball comics made on Krautchan in 2009, FALCO (the person who invented polandball) drew Poland's colors upside down. It's not known whether or not this was done by accident, or if he did it intentionally to piss off the Polish nationalists on that image board. Either way it worked, the Poles got angry about it, everyone else thought it was funny, and it stuck. That is the real reason why Poland is upside down.