As you probably know, water is conductive (hopefully you didn’t learn that the hard way). What this means, among other things, is that you can actually use water as a MaKey MaKey trigger. Leave a connected alligator clip in a vessel of water, ground yourself and stick your finger in the water, and boom!* Water button.
*I promise, it’s quite safe. No actually booms or zaps will occur.
One of the inventions demonstrated in the Kickstarter promotional video for the MaKey MaKey that utilizes the conductivity of water is bucket DDR pads. Another is a “cat photo booth” which uses computer image capture software and the MaKey MaKey kit to snap a picture of a cat when it takes a drink of water from a bowl (see featured image).
I decided to recreate this photo booth with one of my own cats, Amelie. 
Amelie is somewhat obsessed with water and never fails to investigate an unattended drinking vessel, so I knew I’d have a willing participant. I filled a wine glass with water and suspended an alligator clip that was mapped to the left-click button on my computer, with the cursor trained over the shutter button on my webcam software. The key to getting this setup to work is grounding the cat by maneuvering her to stand on an alligator-clipped foil-wrap pad (reused from the DDR pads). This is where we mostly went wrong–Amelie took plenty of drinks but wasn’t quite standing on the pad, and before I could rearrange things she got bored. Eventually, though, I managed to convince her to come back and have another drink. Ta da!
There was in fact one more (fun) hiccup: because I had my cursor trained on the shutter button, and because Amelie didn’t just take one drink, the computer didn’t just take one photo of her–it snapped a photo every time her tongue hit the water. So I ended up with a series of shots that, when played in sequence, make a stop-motion video of Amelie doing her favorite thing: drinking:
Oh, I had a cat like that, around whom you could never leave drinks unattended. Except she was specifically obsessed with RUNNING water, so she would purposefully tip them over before drinking.
MarlowePI, that’s fantastic–I hadn’t heard of that connection before. Amelie is also particularly obsessed with running water, but this mainly results in her hanging out on the bathroom sink starting pointedly at anyone in range until they give in and turn the faucet on, as well as doing what we call her “rain dance,” where she rolls around on the bedroom floor in the evening whining until someone stands up, at which point she runs to the bathroom in the hopes that they’ll meet her there.
For the record, this is my favorite cat with a drinking problem:
http://youtu.be/8KswnjMa-MQ
Oh, our cat would cry for the faucet as well. Unfortunately, if we gave in she would get in the habit and then start crying for it… at 4 AM. We broke her of the habit, but any time we got a new roommate we would warn them that she would cry for the faucet and not to turn it on for her, but they would never believe us. They’d turn it on – “But she’s so cute!” – and then sure enough she start waking them up at 4 AM. One of our roommates kept forgetting not to leave her drinks on her desk and went through, no lie, four keyboards as our cat kept tipping the glasses over on them.
Hah, I wouldn’t be blaming the cat anymore at that point!
My cat Xerxes never used to drink from my water glass..until I lived with a roommate whose cat taught her to do it. My kitten Jin LOVES to play in the bathtub:
[youtube http://www.youtube.com/watch?v=Hsy_TsKtgLE?list=UU366wOigN3YPw2CmASD5gjQ&w=560&h=315%5D
My bf’s cat Boots has always loved to play in the shower after we’ve been in it,a nd has now taught this to Jin. Boots is a yelling cat and yells and yells to make us make the shower wet sometimes. He’s learned his voice is amplified by the shower stall and gets in to yell there.