Unless something has changed recently, the only place to get the Kitchen Sink is at Beaches and Cream---it is (described on AllEars)
Kitchen Sink - scoops of vanilla, chocolate, strawberry, coffee and mint chocolate chip, smothered in every topping we have $21.99
The sundae in BB at Sled Dog Expeditions is (described on AllEars)
Garbage Pail - chocolate and vanilla ice cream, waffle pieces, sprinkles, cookie pieces, hot fudge, strawberry sauce, whipped cream, nuts and a cherry $8.99
On the same order, but I didn't want anyone to be looking all over BB for the one served in a sink. Both very yummy, but you can tell the size difference based on the price difference.