That, in player slang, is – a derivative of the common expression "4 Dragons" meaning the top prize, and "cracked" meaning you shattered the dream. You were one symbol away from glory, but the game denied you.
The 4 Dragon variation became popular because it reduced the complexity of the traditional 6-piece burr into a more compact, 4-piece design. Despite having fewer parts, the unique "cracked" notches make it significantly more difficult than many 6-piece versions. How to Solve the 4 Dragon Cracked Puzzle 4 dragon cracked