I can't tell you how many times this has happened, and I'm sure you can all relate. You're in a group, in an instance, and in (or were in at the time) unfamiliar territory. Your group leader gives the command. You, being a good group member, follow the command that you've been given, only to see "wait!" go by just a split second too late as your group leader realizes that they've made a tactical error in judgment. The only problem is that you are already committed, and there is no going back. The next thing you know you're staring the rez angel in the face, and the rest of your team is either screaming in /p or (more often in my experience) howling with laughter in TeamSpeak at your group leader who just happens to be a (now) very embarrassed guild mate.
I think these kinds of stories are really kind of universal in WoW, no matter what language, countries, or other differences we may have separating us. In my case, I've been involved in wipes in places as varied as Wailing Caverns where we jumped in the wrong place, not knowing you needed to clear all of the Scarlet Monetary Cathedral before you pull Mograine, and level aggro jumping off a balcony pulling huge amounts of the dungeon down on us in BRD.
Of course, my personal favorite involved watching a Shaman say "Check this out!" and putting on Water Walking. He then decided it would be cool to run down the river as opposed to the land as a means of showing off. This, in and of itself, was no real big deal. However when he got to the end of the river rather than stopping he apparently completely forgot that he had Water Walking on and decided to take a swan drive over the waterfall. His intent was to just land in the pool below and swim to the side while the rest of the party had to ride down the cliff path in the Hinterlands. The only problem with this is that if you leave Water Walking on, it tends to makes the water react like you've just jumped onto solid ground. Needless to say that Shaman immediately died, and the guild mates he was showing off to still haven't let him live that one down as yet. (And frankly, we probably never will because he never lets us live ours down, either.)
What famous last word situations have you been involved in? Are there any that your guild mates still haven't let you live down? Anything that made you completely howl with laughter when it happened and still makes you chuckle even now? Share your stories!