Wanting to update this, has been posted multiple times - some is outdated, fixed, some still works.
Get a High-lvl toon, possibly lvl 100 and your twink of choice (lvl 85) and run Stormstout Brewery - or Jade Serpent with your two accounts. Yields the 57k bonus xp per 3-5min depending on how fast you are. Stormstout can be done faster than Jade imho, due to the 1st+2nd boss in Temple..
If you get the 10times dungeon done-lockout, disband group, inv again. Rince repeat.
Works really nice