I lived in Vietnam for about a year. On many major street corners, you could usually find someone selling coconuts. The vendor would pick up a fresh one, chop the top off with a machete, and insert a straw + spoon. While the quality varied, more often than not they were good. That said, it's definitely not a taste everyone will enjoy.

I've been back in the states since June. The coconut juice/drinks sold in the stores taste nothing like actual coconut juice. I'm not sure people would go as crazy over the real thing...but who knows.