Bring your $400+ electronic watch with a non screw down crown in a steamy shower and expose it to high pressure water streams and various soaps.
What could go wrong!
Unless Tim Cook showers in cold, low pressure water and doesn't use any soap - probably nothing.
However, that 'probably' is enough to make me wait a couple of months before leaving it on my wrist in the shower, just to see if those who do, start reporting water damage to the watches. If there's not a significant number of watches being damaged I'll take the risk and rely on applecare+ if the worst happens.