Michael Scott bought himself a “World's Best Boss” mug in The Office. The Dunder Mifflin Scranton branch manager proudly displays it in his office, even though it is self-awarded rather than a gift from his employees.
The mug appears from the show's pilot, when Michael introduces himself and shows the documentary crew the souvenir. He explains that he bought it at Spencer Gifts, turning an ordinary novelty item into a recurring joke about his enormous confidence and questionable management style.
The mug also features in several storylines. Jim puts it inside a gelatin mold as a prank in the pilot, and Dwight accidentally breaks it in “The Secret.” Michael then reveals that he has an identical replacement, suggesting that the supposedly unique award is easy for him to replace.
Michael later gives Jim a matching mug after Jim becomes co-manager in “The Promotion.” The joke is that Michael's mug claims he is the world's best boss, while the series repeatedly shows that his employees often find him chaotic, insensitive, and exhausting—but occasionally sincere and loyal.