Don’t be panic if Spill Water on your MacBook Pro / Air.
Here’s How You Might Be Able to Prevent Liquid Damage
Turn the MacBook Pro / Air Off Immediately
The Mac needs to immediately turn off, assuming it’s still on. Hold down the Power button until the Mac shuts off, or shut it down from the Apple menu. You’ll have to worry about your documents later (OS X Auto Save should do it’s job), right now you’re trying to save the Mac itself.
Unplug All Other Cables / Cords
All external devices need to be disconnected immediately, whether its a display, monitor, external hard drive, even a mouse and keyboard. This is particularly true with powered devices since they could cause a short. Disconnect everything.
IF POSSIBLE, Disconnect the Battery
Most new MacBook Air and MacBook Pro models have internal batteries making this impossible, but if the Mac has a removable battery, take it out immediately.
Dry Off All Visible Water
Now that’s all power sources are disconnected, dry off all visible water completely. Use a cotton towel if possible because it’s highly absorbent, but paper towels can work ok too. Pay special attention to the keyboard because water can easily seep under the keys. Those with technical aptitude, patience, and the proper screw drivers can also attempt to disassemble their machine to dry out components too. That’s probably the most effective method, but it’s far beyond the scope of this article.