To get this you'll have to defeat Princess Kenny (the final boss) while wearing your makeup disguise. The items you have to wear are-
-Makeover Outfit
-Makeover Accessory
-Makeover Makeup
-Makeover Wig
Make sure you have these equiped as the game changes your outfit after you defeat Chef and become King Douchebag. This can be hard to see if you have the Hasselhoff face on as it blocks your character. You can get "Face Hoff" & "Outpatient" achievements at the same time by having these items equipped, the Hasselhoff from Tom's Rhinoplasty, and Dire Aids from Canada.