This might actually be survivable with minimal damage. Lithium reacts with water to form lithium hydroxide and hydrogen, but the reaction isn't nearly as violent as the other metals in its column of the periodic table (such as sodium). So the moisture in your ear canal will cause some burning (both from the heat of the reaction and the corrosive lithium hydroxide) but if you act quickly to pull the two plugs of lithium out it might not be so terrible.

I have the advantage of having a multitool in my pocket that's got a pair of pliers in it, that will help with the extraction should the outer end of the lithium plugs be difficult to get a grip on.

I guess my main concern will be eardrum damage, I have no idea how well it'll hold up to this abuse.

Fortunately lithium isn't one of the *explosive* alkali metals, it just burns in water. So I think I'm going to go with the lithium option here. It'll burn and I may lose my hearing, but it's not going to blow my head off. Better than going blind.