On the unhealthiest end of the spectrum comes the freakshakes—a milkshake with generous amounts of ice cream, whipped cream and chocolate sauce, plus toppings of cake, cookies, donuts and candies. Get one at Black Tap in New York; at The Original Dinerant in Portland, Oregon; at Burger Republic in Nashville; at The Boston Burger Co. in Boston; and at Lunchbox Laboratory in Seattle.