Immediately shut down the MacBook, disconnect the power adapter, turn it upside down to let the water drain, and leave it open to dry. Call us and bring the device by so we can deactivate the battery. Of course, this service is free. Every MacBook has a built-in battery that powers the device even when turned off. The faster the battery is disconnected, the higher the chances of the device surviving the damage. NEVER SHAKE THE DEVICE, as this distributes the water inside and causes further damage. Do not transport it until at least visible water has dried.