Here is the full list of all 13 DeathSpank: Thongs of Virtue achievements.
Watch Both Game Endings
Discover all 44 Teleporting Outhouses
Kill Santa Claus
Learn to Speak Japanese
Go Sailing in a Pirate Ship
Kill the Taking Tree
Reach Level 20
Kill 3000 Enemies
Kill Wortten
Get an Engineering Degree
See all 20 of Madame Primp's Outfits
Kill the Evil Nun
Convince an Orque Guard you are an Orque