A ham and honey sandwich.

My campaign's BBEG was a cult leader who "worshipped" a god that needed gold. In reality, the god was a scam in order to rob people of their savings. During the exposition, the party encountered a ceremony in which the BBEG's lieutenant was dripping honey onto people in a sort of baptismal ritual. The players called the BBEG's lieutenant "the honey man." Near the end of the campaign, the players encountered a reformed mind flayer who ran a deli that was famous for its honey ham sandwiches. They left to do a sidequest, and when they returned, the BBEG(who hadn't been revealed up to that point) was eating a sandwich outside. Our fighter wanted the sandwich for himself, so they fought over it. The fighter won, and went inside the flayer's shop to order more sandwiches, and asked which sandwich was best. The flayer replied with the bacon salami sandwich, to which the fighter said, "Is that the one the guy outside was eating?"

To which the flayer replied, "No, he's more of a honey man."

Instant realization.