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