The Legend of Argyle (S1E13)

When the away team beams down to the charred ruins of a desolate planet, they find body parts strewn everywhere that end up belonging to Data's twin brother, Lore. After assembling him they find out that like all pairs of twins, one is good and one is evil. But after giving Lore the full, unsupervised run of his ship, Picard is most concerned with Data's loyalty. The crew needs to figure out whose side he's on fast, because there's a glass pinecone that is bent on destroying the ship. Will Tasha Yar sleep with Lore, too? Will killing a tree save them? It's the episode where we finally inherit the "Shut up, Wesley!" drop (and relay a story we heard about our favorite actor, Biff Yeager)!