Jug

The Jug is a major object in Epic Mickey. Not only did it contain the Thinner for the Thinner Disaster, it's also the Shadow Blot's prison.

Mickey's Mischief
The Jug originally belonged to Yen Sid, containing Thinner. When he was done with it, Yen Sid would dip his paintbrush in it to clean the Paint off it. However, when Mickey snuck into his workshop and accidentally created the Shadow Blot, the mouse grabbed the Jug and splashed its deadly contents at the Blot, melting him enough to be absorbed by a sponge. When Mickey tries to clean up afterwards, he grabs the pot of Paint and pulls it toward him to hide the sponge in. This bumps the Jug and causes it to tip over and spill Thinner on the model of Wasteland. The spilled Thinner melts the barrier separating the Toon World from Wasteland and creates a portal into it. The Blot escapes the sponge and slips through. As there is a lot of Thinner, the hole expands until the Jug falls in as well.

The Thinner Disaster
For some unexplained reason, the Jug is bigger in Wasteland than it is in the Toon World. So much bigger, in fact, that when it falls into Wasteland and smashes on impact, the remaining Thinner forms a gigantic tidal wave. It ravages Wasteland, even wiping out a few toons. Of course, the Shadow Blot comes alongside it, making it that much worse with the Blot Wars.

The Blot Wars
After Oswald the Lucky Rabbit loses the Blot Wars, he comes up with a new idea: Fight the Blot again on the highest peak of Mickeyjunk Mountain and imprison him, using the newly-repaired Jug. Oswald and Ortensia carry out this plan, but as they're trying to seal the Blot in the Jug with a cork, Ortensia sacrifices herself saving Oswald from the Blot and is turned into an inert statue. Oswald finally seals the cork enough to trap the Blot, but not enough to stop the Blot from spawning countless minions and a second-in command. It is then that Oswald exiles himself to Mickeyjunk Mountain to guard the Jug and makes sure the Blot never escapes.

The location is convenient, for Oswald, being a rabbit, can climb to the Jug's location relatively easily, but the climb is practically impossible for anyone else to make.

Trivia

 * During early development, the Jug looked more like an actual thinner jug, but for unkown reasons it was changed to its fantasy design in the final version.
 * The Jug reseambles The Bottle from The Rescuers