Try the dishwasher. See this post on 43 Folders for more.
I’ve been a believer that water poses little harm to electronics, provided that the water’s clean and you dry thoroughly to avoid corrosion, but I never would have guessed at this. I mean, cure powder-coat in the oven? Sure. Confidentially destroy CDs with the microwave? Absolutely. (But air it out carefully afterward, and don’t even think about breathing the fumes!) But a keyboard in the dishwasher? Yow.