Can I put my keyboard in the dishwasher?

Short answer: No

Long answer:

I would highly advise against it. If you are looking to clean it either use compressed air cans designed for PC cleaning or take the keyboard apart. Most of the time there are a few screws on the bottom of the keyboard you can just take off and separate it. Then just use compressed air or shake out all the nasty stuff.

NO!!!!!!!!!!

Only if you want a nice keyboard-shaped doorstop.

Can you? Yes. It is physically possible.

Should you? No.

There are dishwasher-safe keyboards out there, if yours does not say, read this article before you decide to try it.

unless you want to be bored for no reason.

I would not suggest just throwing the whole keyboard in the dishwasher, there are parts to a keyboard that can be a bit sensitive to thin films of soap or wetness in general.
If you really want to do this, I completely agree with battlemarz that you should open the keyboard and just wash the parts.
When I do this I first remove the key plates, (most PC keyboards I have encountered have these) and put them on the bottom rack of the washer, right above the jets. They usually will come off easily and all of the keys will be set in the plate so they wont fly out when they are in the machine, (note: you might have to go top rack if your keys are held weakly or if you have monster dishwasher jets). I also throw the little silicone bubble things into the silverware catch basket with the mesh lid on it, and perhaps even the outer housing if I am feeling particularly obsessive.
You do not want to put the dual layer of contact sheets into the wash (usually a clear plastic with silver wires), Because even a super thin soap film can cause errors in key press registering if you type lightly. I usually wipe these down with a damp fine cloth (read: no soap, no toilet paper). You also really don’t want to put the controller board through the wash (the board where the USB comes in… or any circuit board you find in the board for that matter.) and unless you know what you are doing you probably want to avoid getting it wet.
If you do put the silicon bubble sheets in the wash, make sure to stop it before the drying cycle… I don’t know if it will get hot enough to melt the silicone, but it is better not to take the chance.
Also: After the wash is done make sure you wait until the parts are super dry before putting them back together or plugging the thing in.

As long as it is not a wireless keyboard and you don’t heat dry, you can. I never have done this myself, but have brought several keyboards back form the grave by a fresh water wash. Simply just take the keyboard to the sink and rinse it thoroughly until all goo has been washed away. I then put it upside down on a towel (or a vent of some kind) and let it sit for three days.
I have saved keyboards from soda and coffee spills on many occasions this way.

i had a friend that used to do that all the time..he said it works great…as long as you let it dry out before you use it, it should be fine…just put it in the top rack and don’t use soap.

Just be careful to plug it back when it 110% dry!