polandball
Used here to refer to the character, for the comics in general see Countryball.
The effective 'star' of Countryball, being the first to be created and the start of the webcomics when it first appeared in late 2000s, to the point Polandball is an acceptable way of referring to countryball comics in general.
Jokes typically associated with Polandball include "cannot into space," referencing Polish migration to the UK and taking of lower class work there by having him be UKball's plumber, and having the Polish flag be drawn upside down as a comment on the Polish being very backwards, incompetent and a little naive (all tracing back to Polish jokes and stereotypes). The flag being drawn upside down is why, unless the flag appears regularly in a post, Polandball by itself shouldn't be tagged as Polish flag.