Joel: Is that a jar of nut milk?
Michael: No
Jack: Then why is it crusty Michael: It’s old. Try it.
Jack: Ok
Michael: HA! YOU JUST DRANK NUT MILK!
Jack: AAAAAAAAAAAAAAAAA
EBK stands for "Elite Ball Knowledge." 1 In internet slang, "ball knowledge" originally referred to a deep understanding of football/soccer or basketball, but it has evolved into a broader term for having a highly sophisticated, deep, or niche understanding of any specific topic (such as music, movies, or subcultures).
Person A: "That scene was a direct homage to an unreleased 1982 Japanese indie film."
Person B: "Wow, EBK."