Shiboomi

Shiboomi is a fiendishly complicated card game, dating back at least to the 1960s. The rules are many and unclear (described by Middleman Guy Goddard as "Byzantine"), involving such diverse elements as:
 * Every player being dealt a full deck of 52 cards
 * The only known hand is "52 of a kind"
 * Live rabbits
 * Elaborately dressed dealers, who hand out the above-named items on silver platters
 * Houses of cards (called a "siege")
 * A moderator, who does not play, to "call" the game

Aside from Guy Goddard, those who know how to play Shiboomi include:
 * Wendy Watson
 * Lord Jeremiah Purcell
 * Anatol Gogol
 * Vilma Schnipp
 * The Scot
 * Count Manzeppi

Some games of Shiboomi are incredibly high-stakes, particularly those hosted by Purcell. Such games involve extremely valuable and sometimes unique (including gigantic jewels, the missing 18 1/2 minutes of the Watergate tapes, and the schematics for the lunar landing sound stage), and being decapitated if one fails to understand the rules or cheats.