I used up a plastic bottle of vinegar, and thought the bottle might make an interesting sound, and it sort of does. So I sampled it.
There are two hits; one with finger meat, the other with fingernail. Then there is a electric keys type of sound I made using a hit sample with the Tone Machine in Kontakt. Also there is a cymbalish sound, or sound effect, made from a breath I made in the recording while sampling.
I have to say, the key's sound isn't all that spectacular by itself, but I layered the keys sound and the dull hit with a nice grand piano, and the vinegar sounds really make the magic happen. Give that a try, see what you think.