WoW was my first RPG after playing FPS games for years. Needless to say, this made for all kinds of numbskull hilarity.
My fondest noob memory though came while leveling my very first toon (mid-TBC). Under the watchful supervision of my girlfriend's 70 priest, I'd just gotten my mage to Southshore and, after managing to aggro several murlocs, I thought it'd be an awesome idea to conjure water on them. I was quite surprised and disappointed to learn that the spell didn't match what was running through my imagination. Meanwhile, she nearly died laughing.
P.S. -- This was about two days after someone asked me "What's your spec?" and I answered "Tailoring."