I Solemnly Swear That I Am up to No Good™! This Harry Potter mug features the password to open the Marauder's Map on one side, and the phrase that closes the map, Mischief Managed™, on the other side. The design is complimented by footsteps. The black ceramic mug holds 11 ounces of your favorite hot or cold beverage and is microwave and dishwasher safe.