What does 국뽕 mean?

 ANSWER: ultranationalism

Wikipedia says HERE that 국뽕 (國뽕) is a new derogatory term used to refer to Korean ultranationalism. The word is made up of 국 (國), which means "country," and 뽕, which supposedly comes from 히로뽕, and that refers to crystal meth or methylamphetamine. So, 국뽕 suggests "intoxication on nationalism." 

The following video shows three "foreigners" trying to explain in Korean what 국뽕 means, and they do a surprisingly good job of it.

In 

In the past, when foreigners could speak very little Korean, they tended to repeat many of the nationalistic claims that Koreans made about their country and culture, but as more and more foreigners become more familiar with Korean culture and history and become more fluent in the Korean language, they also become better able to question some of the nationalistic claims of Koreans in general, as the Korean video below talks about. And it seems that the foreigners' opinions are starting to cause some Koreans, themselves, to question their nationalistic tendencies and some of their excessive bragging about their successes, and that seems to result in words like 국뽕 and 팔불출 being used more and more often.