I am not sure what "double nudge" means apart from the obvious meaning of two nudges. There is an expression "nudge, nudge, wink, wink" which is a way of describing something someone says that has a double meaning. For example, a statement that has an obvious literal meaning but then a hidden meaning, perhaps sexual. Saying "Nudge, nudge, wink, wink" particularly as you nudge and wink at someone is a way of saying "do you see my secret second meaning"?
Does that work in your context? If not, maybe you could fill in some more details?