There was a game called Arcanum released about 9 years ago. Played really similar to Fallout 2 or Baldurs Gate.
I made a character in it that was intentionally supposed to be big tough and stupid. I succeded well beyond my intentions, especialy in the third aspect. I named him a good and proper half-Ogre name, Martok. However, with such a low intelligence the poor guy got called dumb ALOT. So much, in fact that he began to think that it was his name. Seriously! On the stat screen for the character it actualy changed from the original name to read "Dum". The dialog would have him introduce himself by saying "Me am Dum." or "Hi, me Dum!"
This is an actual conversation I remember with a merchant:
"Hi, me Dum!"
"I can see that, but whats your name?"
"Huh?"
"Oh, um, nevermind. What can I do for you, Mr....Dumb?"
"Me want shinies!"
(Entered the Bartering Menu)
The game also often had me overpay for items (because he couldnt count), but would almost just as often offer a discount from the nicer merchants.