Slahtz

Slahtz is a Forsaken found lurking at the Barracks in Orgrimmar's Valley of Honor. Slahtz gives members of the Horde access to an option that allows them to turn off experience gain in the game in any form or fashion. The fee is to turn on or off each time.

Quotes
There are some who desire to stop gaining experience from their actions; to forever remain at the level of strength they are now, and never grow stronger.
 * Gossip

I can make this possible... for a fee, of course.

But understand this: Once you pay me, you will NO LONGER GAIN EXPERIENCE. None. Not one whit.

Should you change your mind afterwards and want to start gaining experience again, I can undo the process for the same fee.

Depending on if experience is disabled or not, one of the following gossip options will display:
 * (fee:, will apply Experience Eliminated)
 * (fee:, will remove the buff)

While standing around, Slahtz will randomly emote some thoughts that are fairly common to level 19 twinks:
 * emote
 * emote
 * emote
 * emote

Guild XP
Turning in quests continues to award guild experience and reputation normally while personal XP gains are disabled.

Trivia

 * His Alliance equivalent is Behsten. "Behsten Slahtz" is a homophone for "best in slots".