Dungeons & Dragons is the hobby that occupies the majority of Mordicai's freetime.  It is slang for the entire genre of "roleplaying games" as well as a roleplaying game in specific.  The basic conceit is that a group of people get together to pretend to be fictional characters (the Player Characters), while one other member of the group (the Dungeon Master) controls all other aspects of a pretend world; that is, while the player characters are the stars of the story, the dungeon master is the director, as well as all the extras & supporting cast.

Mordicai gets together every Sunday for around eight hours to play D&D.  Every other Sunday he is the dungeon master; his players are Bernie, Gerd, Mike, & James.  On opposite Sundays Mike is the dungeon master, with the sometimes addition of Tom.  Other players have some & gone, & some have guest starred: Scott, Christopher, Antonio, & Kingtycoon for example.