If you're looking for a solution, the walkthrough will provide a great help with that. I did want to point out one odd issue I came across.
While I was doing this achievement initially, I had the "Palm Tree" joke but, when I tried to talk to the tree, the unique dialogue didn't pop up. I reloaded a save from just before talking to him and listened to every bit of dialogue that is outlined in the guide and I wound up getting a new joke, with the prompt at the end for the achievement.
Just wanted to put this there for anyone struggling to get it.