OK, this is basically a root beer float minus, uh, the root. The Shake a Leg gets its name from Heavy Seas Peg Leg Imperial Stout, to which is added vanilla ice cream and-this is an Italian joint after all-some amaretto. Seriously, stop scowling. Unwrinkle your nose. It works, thanks to the stout's coffee and cocoa undertones, which pair well with the creamy vanilla. The amaretto shot provides that extra kick of sweetness. And speaking of kicks, Peg Leg packs an 8 percent-ABV punch. Think of the dessert as a "beer" best shared with two spoons.