Wand of Wonder... aka Adventure Hoser on a Stick. Any player willing to use it in the first place just has that itch to see what it'll do next, usually to the dismay of the rest of the party.
Most memorable use of the wand by a player in my high school campaign:
Giant, animated statue of a lion had the characters trapped in a room, but couldn't get at them because it was too big to fit through the doorway. Player decides to use WoW "safely" at a distance, but it shrinks the statue so it can come through the door! Paniced, the player fires the wand again, and turns the charging lion ethereal, rendering it harmless, which wouldn't have worked without the shrink first (original size exceeded the ethereal effect's weight limit) or if it was a living creature instead of a statue. Talk about lucky combinations.