brashiest
Least shy person
Brashiest is the superlative form of brash, describing someone or something that displays the most aggressive self-confidence or tactless boldness.
A person who is the brashiest in a group shows the least restraint in asserting themselves, often coming across as arrogant or insensitive to others.
He was the brashiest salesman on the floor, interrupting colleagues and dominating every meeting.