Is your friend easy on the eyes? This is Apple's explicitly stated policy on water damage:
http://support.apple.com/kb/ht3302If an iPhone or iPod has been damaged by liquid (for example, coffee or a soft drink), the service for such liquid damage is not covered by the Apple one (1) year limited warranty or an AppleCare Protection Plan (APP). iPhone models and iPod models that were built after 2006 have built-in Liquid Contact Indicators that will show (as described below) whether the device has been in contact with water or a liquid containing water.
I've known several iPhone owners who found Apple customer support to be merciless in their policies towards replacements. Maybe your friend got lucky?