I think The Crazy 88s is a reference to the word Yakuza itself, like a way of saying they are doubly badass:
"The term "Yakuza" comes from a Japanese card game, Oicho-Kabu (played with hanafuda or kabufuda cards), and means "good for nothing". Similar to baccarat, the values of the cards are added together and the last digit of the sum is taken as the score. The worst hand in the game is a set of
eight, nine and three, which gives a sum of 20 and a score of 0. In traditional Japanese forms of counting, these numbers are called Ya, Ku and Sa respectively, thus the origin of the word "yakuza". The yakuza took this name because the Ya-Ku-Za hand requires the most skill (at judging opponents, etc.) and, obviously, the least luck in order to win (i.e., the hand is the worst that a player can receive based on luck of the draw, so only a consummate expert could have enough talent to counteract his bad luck and still win with such a hand.) The name was also used because it signified bad fortune, presumably for anyone who went up against the group.