In Chapter 2 when you got all the ingredients for the Volcano Beserker drink, head to the bar and look at the cocktail menu which you got earlier to order the drink. Try to pick it up and Harvey will appear to prevent from drinking. You have to hypnotize him with the yarn. Then you are back to the hypnosis world.
Make a SAVEGAME here just in case anything glitches out.
Then you can drink the coffee to get back to the real world. Make sure to at least see all the cutscenes ones to prevent the game from glitching. Afterwards repeat the process of drinking the Volcano beserker, hypnotizing Harvey and drinking the coffee about 15 times to finally unlock the achievement.