Was the egg raw, or cooked? That makes a great deal of difference in how I think about how awful your experience was.

Not a keyboard, but: Many years ago, I worked for a company that was using microwaves on living tissue. They used salt water (saline solution) to simulate blood - it has a similar thermal reaction to microwaves. We had this VMEbus rack with various circuit boards in it. The top card in the rack was the graphics cards. And we had this VMEbus rack without the top on in the lab, so we could get oscilloscope probes onto the circuit boards...

I happened to be looking at the monitor when the tub of salt water got dumped onto the graphics card. I suspect it looked something like an acid trip (don't have any actual experience to go by).

They turned off the power, rinsed the graphics card with distilled water, then dried it in an oven at about 150 F to dry it out thoroughly. It worked after that.