Mine has to be:
"WTB UNIDENTIFIED WARRIOR SUPER ABSORBTION RUNE!"
I pm'ed him to think about what he just said, he caught on after saveral minutes.
Another was when this guy wanted to buy my clean 15-22 req 9 fellblade.
"I'll trade you this perfect hammer for your fellblade(was kinda excited at this point, it was rams but wth), now where can I buy a 15>50 mod for this fellblade and how much do they go for?"
I could've bullshi tted at this point so I could get the hammer, but I just couldn't do it, I told him you can't buy a 15>50 mod and its inherent, then he declined to buy the fell

funny thing is that these guys actually have their 15k armors at this point.
other notable mentions:
"WTB 15>50 un'id weapons"
"WTS xxx item for ___overcharge__ ; WTB xxx item for ___really low ball__" in same message
"Newbie looking for guild! must have teamspeak, hall, cool capes, in the top 100 guild and lots of active member! pm me!" - yeah, you'll get tons of invites
"where do you get FOW armor?" - I pm'ed someone to tell them its in UW, I'm not the only one.