Hank Panky is a colloquial term meaning deceitful or dishonest behavior. There are a multitude of synonyms one could use in place of this term, such as shenanigans, mischief-making, or tomfoolery. Other options might include skullduggery, monkey business, or chicanery. If you're looking for a more formal synonym, terms like fraudulence, duplicity, or mendacity might fit the bill. No matter which term you choose to use, they all convey a sense of trickery or underhandedness, making them appropriate choices when describing someone engaging in dishonest or unethical actions.