On the 4th day of cumming...have an Ice Xmas!
Put on some cute underwear (preferably semi-tight) and get three ice cubes or an equivalent amount of snow, then put it down the front of your undies.
Enjoy some media that turns you on while you wait for the ice/snow to melt. It must be completely liquid before you're allowed to touch your naked cock, though you may rub yourself over your underwear lightly while you wait if you like.
Once the ice/snow has completely melted, go ahead and get one more ice cube/bit of snow, and keep that in your masturbation hand while you jerk off to orgasm!