Party Animals

Wilson can be found pretty early into the level.

After navigating the dock, you'll come across a campfire with two pirates guarding Wilson. Grab Wilson (the volleyball) for a second or two and you'll unlock the achievement at the end of the level. If you climb up the ladder to where the bridge starts breaking, you've gone too far.

Do note: if for whatever reason you hit start and "respawn" this will void the achievement and you'll have to replay the level again (dying and getting the "Wasted" screen is okay).