.. Water cooler (of doom)

Drink it! Drink it to death!

Brutal, but not stupid.

You need a mug. Not the one on top of the books, because... Well, try to find a mug somewhere. ( There is a mug in the left cupboard, near the fridge. )

But it doesn't work with the water cooler. It has to be an official cup.

Now, drink the water cooler to death!

Look around. It must be getting replacement water from somewhere.

Makes sense, yes. Cut the water supply.

Use the Krusz army knife on the hose to cut it. Now you can drink the cooler to death with the official mug!