I dont know everything specifically that is in the Kitchen SInk nor do i know the portions but here is a guess at the nutrtional breakdown
Ice cream Approx 250 per 4 oz portion ( i am guessing 8 scoops at 5-6 oz portions) = 3000 calories
Marshmellow Topping 322 per 3.5 oz portion = 322 calories
Strawberry Topping 55 per tablespoon ( guessing 4 tablespoons) = 220
Pineapple Topping 357 per 3.5 oz portion = 357
peanut butter 75 per tablespoon ( 4 tablespoons) = 300
hot fudge 110 per 2 tblsp ( 4 tablespoons) 220
butterscotch 252 per 3.5 oz topping = 252
choc syrup 279 per 3.5 oz = 279
whipped cream 220 per 3.5 oz = 220
choc sprinkles 35 per tblsp ( 4 tablespoons) = 140
cherries 25 per oz ( 4 oz ) 100 calories
For a grand total ( and a low guess in my opinion ) of 5410 calories
Ok...but except for the guy in the post directly below yours that ate it himself....MOST of us are gonna have to share it with several other people. So....4 people sharing would be 1,352 calories each.
And before someone gets upset about that number (since it's about 2/3 of what a normal calorie intake should be)....consider this:
McDonald's Big Mac meal, upsized to large: Big Mac 540, large fries 500, large coke 310 (no refill)....total....1,350 calories. (anyone ever NOT gotten a refill of soda??? and ok, I'll grant you a diet soda would be much less calories, but get the point?)
or
Burger King meal: (single) Whopper with cheese 760; medium fries 360; medium coke 190 (no refill): 1310
I could go on....but basically since I think that 1/4 of a kitchen sink would definitely fill you up instead of a meal, it's no worse than eating a typical fast food meal. Ugh.
Scary eh?
The thing looks like a big mess to me, and some of the flavor combos aren't at all appealing. I've never had the KS, but I can't tell you the number of times people who have ordered it say it just turns into a sweet bowl of glop before they could finish. Maybe if you had half dozen or more really ravenous folks you could finish...but oh the ice cream headaches. 
