Poland/Hungary is a semi-popular and heterosexual pairing in the Axis Powers Hetalia fandom. They have never appeared together in canon, but are shipped together due to their histories. Recently their profiles have mentioned that the two of them are on very good terms with each other.
The fact that Hungary is a tomboy who seems to like effeminate males while Poland seems to have a tendency (at least in the early strips) to cross-dress, something fans cite to justify the relationship, is not a coincidence. Himaruya's original concept for Hungary was a cross-dressing male, while Poland was a female. When he created a female Hungary, he used that idea for Poland instead.
Currently this is the only time that they have been shown to talk to each other in the manga. Hungary refers to Poland as "Po-chan" ("-chan" is an honorific used mostly for children and/or close friends) so this suggests familiarity and affection between them.
Poland and Hungary have had close relations since the Middle Ages. This friendship is not only described by a bilingual proverb ("Pole, Hungarian, two good friends"), but it also has its own holiday celebrated in both countries on March 23.
Webcomic: Main Storyline
Tannenberg Sequel (Axis Powers Hetalia volume 3)
Webcomic: Extra Stories
Webcomic: Comic Diaries