It depends on what your previous weeks prep is like. Do you mean ice cream the same day as the show?? I usually have fat free ice cream with choc sauce on the evening before the show as part of my muscle refilling, but it depends on whether you manipulating sodium and potassium or not, and whether you've been dieting with very low fat or not, and depends on how much you're going to restrict you water or use diuretics. As a general rule of thumb you should avoid introducing anything into your diet that you haven't done a trial run with to see how you respond. If you haven't tried ice cream before, then you should just stick to foods that you have been dieting on. If it's a sugar rush you want on the day of the show, then ice cream is prolly not the best bet. Save it until after the show. Try some niacin and jelly beans instead.