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While investigating the Men of Letters, Sam and Dean find the group's secret headquarters. As they set up shop, the brothers discover that a rabbi, Isaac Bass, spontaneously combusted and had ties to the Judah Initiative, a secret group that fought Nazi necromancers during World War II. When the brothers investigate, they meet Isaac's grandson Aaron... and the clay golem that Isaac gifted to him.
Aaron Bass: What, do you two just break in wherever you go?
Dean: Our dad wanted us to have a solid career to fall back on just in case this hunter thing didn't pan out.
Sam: Why don't you screw yourself, Nazi bastard?
Commander Eckhart: Can we... could we put the Nazi thing aside for the moment and just talk about this like...?
Dean: Nazi necromancer dicks? Pass.
Dean: Now we know. Paper beats golem. Fire beats undead Nazi freaks.
Dean: Sammy, I think we found the Batcave.
The Batcave, first seen in Detective Comics #83 (1944), is the secret underground base of the Caped Crusader.
Dean: In his corner, hacking out his Da Vinci code.
The 2003 novel by Dan Brown dealt with a secret society within the Roman Catholic Church, and involves several ciphers, anagrams, and number puzzles.
Shannon: Yeah, like from that World of Whatever that my little brother is always playing.
World of Warcraft is the most popular of the MMORPG games, and involved players using fantasy characters to explore a virtual world and fight each other.
Dean: I'm Agent Bolan.
Marc Bolan is the lead singer for the rock band T. Rex.
You mean how do we "Oh, no! Mr. Bill" over there?
Mr. Bill is the clay figure that is tormented by Mr. Hands and Sluggo on a series of skits on Saturday Night Live
Dean: I didn't see any letters on Clayface.
Clayface is an alias used by several Batman villains, all of who are made of a clay-like substance and can shapeshift.