A bit offtopic, but as Polish I have to say, that this joke is a bit senseless, becouse of this guy :
Yup, Poland really CAN into space
What's the sense of laughing at something what isn't even true?
+1
It's not about Poland not having sent anyone into space, it's about the failure of the Polish space program as a separate entity. Anyway Polandball seeks to make fun of exactly the type of people you guys are, nationalistic Poles. Bad English doesn't apply to you guys but it was added to the joke because of a Polish user on Krautchan who had horrendous English and always went on rants about how Poland was the best thing ever. Read more into the joke, it's not as sinister and anti-poland as you'd like to think. There are also countryball jokes about the USA, Britain, Russia, France, Germany, and almost every other country.