Fake Irish spelling of "crack" meaning fun, news, gossip, banter etc. Used by plastic paddies and those ignorant of there own language. "Crack" or "crak" originates from middle English and has been used for centuries. The first known use in Ireland is in the 1950s, using the correct spelling "crack". "Craic" first appeared in the 1990s.
When you are taking notes in school, and you are thinking of a penis, and writing network. even tho the a and n in wank are not even near the o and the r.