firt of all, DONT try to switch it on! BTW, what kind of ipod do you own,shuffle,nano,mini,photo,video,classic or touch?
Next, please dont understand this question wrong, was it a black coffe or with milk/whitener or sugar/sweetener? If it was black coffe, it should dry out completely. To do so, put it in a ag with uncooked rice for a couple of days. Take a look at it, if the bubbles are gone or not. If not, leave it in the bag for a couple more days.
If there was milk or sugar in the coffe, the iPod needs to be opened up and cleaned. How to open the iPod can be found in the "repair section" of this page.