Are all cell phones waterproof?

What is the deal with people dunking their cell phones in water? Today, I had lunch with a friend of mine who forgot that his cell phone was in his pocket before taking a dip in the local swimming pool. He realized his mistake some 20 minutes later when he got out of the pool. Of course, the phone was dead, so he headed over to the Verizon store to replace it. Several (unhappy) hundred dollars later, he was up and running again. A few days later, he pulled out his "dead" phone, put the battery from the new phone in, and bam, it was working like new. "Well [insert expletive here]," he said, "I'm gonna return this new phone and just replace the battery." Now, this isn't the first story I've heard of a cell phone that took a swim, appeared to have died, then miraculously came back to life. A coworker of mine admitted to dropping her phone in a toilet (albeit a clean one), fishing it out, letting it dry off, and having it work like a charm. For me, this begs an interesting question: Are all cell phones waterproof?

Anyway, feel free to share your resurrected cell phone stories with us.