Emoticons on domain names

I recently came across with a really strange campaign on the Internet (http://ift.tt/1829cN6) in which CocaCola is giving away .ws domains that contains emoticons:

How is this possible? I know you can register domains with accents or other latin characters, but emoticons?

And most important: how can I visit these kind of websites from my phone or PC if there's no such character on my keyboard?

Thanks in advance!