Things you expect in pawn shops: jewelry, electronics, and nuclear bomb parts.
Wait, that last one isn't right. No one expects to find nuclear bomb parts in a pawn shop. But in this scene from Pawn Stars, Rick calls in an expert to assess whether the cover for a B-57 nuclear bomb is authentic.
On its own, the cover for a B-57 is no more capable of being used as a weapon than a pen cap is of writing, so it's perfectly safe to buy and sell. Of course, it's also hard to find a use for nuclear bomb parts without any nuclear bombs.
See Pawn Star Rick negotiate the purchase in this clip: