Exploding whale most often refers to an event at Florence, Oregon, in 1970, when a dead sperm whale (originally reported to be a gray whale) was blown up by the Oregon Highway Division in an attempt to dispose of its rotting carcass. This incident became famous in the U.S. when American humorist Dave Barry wrote about it in his newspaper column after viewing a videotape of television footage of the explosion. It later became well-known internationally when the same footage circulated on the Internet.
There have also been spontaneous explosions. The most widely reported example was in Taiwan in 2004, when the buildup of gas inside a decomposing sperm whale caused it to explode in a crowded urban area, while being transported for a post-mortem examination. Other exploding whales have been written about and documented by several well-known authors.
Oregon Video: http://tinyurl.com/yn27jg
Taiwan Video: http://tinyurl.com/742jr5