Nananana
Sink 5 putts in a row in the putting practice without mulligans, or using Place Ball.

1. Start a Putting Practice session:
   
   
   
   
2. Change the Putting Practice difficulty settings to have Beginner Swing Difficulty and Unlimited Putt Preview:
   
   
   
   
   
   
   
   
3. Once on the green, line up your putts and then use the Putt Preview to view the projected putt line. Keep repeating this until you have the putt lined up:
   
   
   
   
   
   
4. Repeat this process for five holes in a row and you will unlock the Nananana secret achievement.