For me, amusingly enough, my most embarrassing moment actually had to do with a clam. We were in UBRS (back when UBRS was still hard and let you run 15-man groups) and one of our warriors got bugged while looting. While it's fun to watch someone scoot around in the looting position, it's not too good when it's your main tank. At the time the only real way to get out of the glitch was to carry a clam with you, open it and close it without looting. Being the only female in the raid - and not even thinking about it first - I cheerfully offered to give our main tank the clam I carried with me since he was grumping about being stuck.
As you can imagine, you could hear a pin drop on vent as 14 guys pondered this statement.
If I could have crawled under Azeroth to hide right about then, I would have, as it dawned on me that I'd not qualified that statement enough. I sputtered out about how opening a clam without looting it and then closing the window fixed loot scoot and... yeah. The damage was done. The entire raid broke into hysterical laughter at my obviously flaming embarrassment. I was mercilessly teased for months about it, and as you can imagine, word spread so that it wasn't just my raid group who got to poke fun at me.
To this day I don't talk about clams in /guild.
So with my story told, it's your turn! What's the most embarrassing thing that ever occurred to you while playing World of Warcraft? Did your friends let you live it down, or do they still poke fun at you for it? Share your tales!