chutzpah — extreme self-confidence or audacity; brazen nerve

a person in ripped jeans and a wrinkled t-shirt confidently sits at the fanciest table in the restaurant. They loudly snap their fingers at the formally dressed waiter while putting their dirty sneakers up on the pristine white tablecloth. The waiter's eyes widen in shock as crumbs fall from the customer's shoes onto the expensive table setting. Other well-dressed diners turn to stare with expressions of disbelief and horror. The customer continues to act completely unbothered by the inappropriate behavior, even smiling smugly. extreme self-confidence and brazen nerve in a completely inappropriate situation