In her debut special, “But Sir,” Tamar Rubin emerges as an exciting new talent in comedy, characterized by her bold and lively approach. She blends a raw, punk attitude with the finesse of a seasoned performer. Rubin’s rapid-fire delivery seamlessly navigates topics such as the experience of holding down low-paying jobs in your twenties, the pitfalls of dating, and the impact of being a theater enthusiast during childhood on adult life.