Okay, this didn't grind my gears - I just found it highly amusing...
When I worked at Lockheed, they started an initiative to help young employees network with each other, so they sent out a mass email (*not* BCCed) to hundreds of young employees to let them know about the upcoming opportunities. Within an hour, there were about 100 messages in my inbox, ranging from "this is a great idea" to "let's have drinks tonight at Billy Bob's Bar" to "please take me off this list," and, my personal favorite, "I'M NOT WEARING ANY PANTS!!!!" Only after that did the secretary for the VP who started the networking initiative chime in to point out that the VP himself was also on the list and that perhaps a little more professional decorum was in order. There were then about 15 people who replied-all to apologize for replying-all. America's best and brightest, no doubt...