Conjunction of 'Friday' and 'Cliffhanger'.
A
particularly suspenseful ending to a TV show or story that occurs on the Friday episode so that the audience must wait the entire weekend before the conclusion/resolution.
Coined (possibly as a typographical mistake) by the subscriber 'dabbeljuh' to Max Barry's book Machine Man, which is being delivered a page a day to
subscribers until complete, which typically has a 'Friffhanger' every week.