This can be completed as early as Day 76. When you start Day 76, head north toward Beartooth Point. About halfway there (between the words "Thorofare Trail" and "Telephone"), the trail splits once and then again. After the split, look for an old outhouse that is falling apart (it contains the lyrics to Ol' Shoshone inside). From the outhouse, head east and look for an old cabin that is falling apart. Inside, go into the basement and open the stove. A raccoon should jump out and the achievement will unlock.