He rubbed the magic lamp to summon the 'genie'.
(..) Tell him the truth. It's the only thing standing between you guys. Tell him that I'm a witch? I can't do that. What if he can't handle it? It's not like I can put the genie back in the bottle. He's not gonna turn you in to the warlock police. At least you'd know how he feels once and for all. (..)1998 TvShow: Charmed Title: The Truth Is Out There... and It Hurts Season: 1 Episode 8