The Volunteer - Velen
Quest Giver: Oxenfurt Notice Board
Other Requirements: N/A
You can accept this quest from the Oxenfurt Notice Board or one of the other Notice Boards across Velen. For this quest you'll need to head to one of the small islands west of Oxenfurt and speak with the Rock Troll that is here named Trollololo. Depending on what dialogue options you choose with him you'll either have to fight him or help him by bringing him some paint.
The paint that you need can be purchased from a merchant in Oxenfurt, follow the white dots on your compass to find the merchant then return to Trollololo and give him the paint. The quest will conclude with either the troll painting himself or Geralt painting him.