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
Get an Engineering Degree
Kill Santa Claus
Reach Level 20
Go Sailing in a Pirate Ship
Kill Wortten
Learn to Speak Japanese
See all 20 of Madame Primp's Outfits
Kill the Evil Nun
Convince an Orque Guard you are an Orque