At the end of the game, Norton will demand a hat. He only accepts a few specific ones.
Give him the Silver-Plated Turnip Crown. You would've gotten this by digging up the Turnip in the prologue (talk to Cactus Bill to get a shovel) and then taking it to the Silver Plater to be plated (for 5,000 meat or 20,000 in hard mode).
Give him the Gold Tooth Crown. You get this from collecting a whole bunch of gold teeth from skeletons (the Daveyard is a good place to grind for these) and asking a girl at the Fort of Darkness tents to turn it into a crown. (For 10 teeth you get a tiara which is not the same thing. You need 25, IIRC).
Give him the Necromancer's Crown .
Give him the El Vibrato Crown. You get this from powering up the Roberto Containment system