a party person
a confident person who has a good relationship among others
This word comes from an English word — insider.
This word is a kind of Konglish(Korean style broken English).
‘핵인싸(haekinssa)’ is used to emphasize its meaning. Literally, 핵 means ‘nuclear power’ and it is often used as prefix in Korean buzzwords.
Group is considered as more important thing than each individual in Korea. So Many Koreans worry about their bad reputation in the community and try to become ‘인싸’ who keep good relationship with others.