The phrase "stick in the mud" refers to someone who is unadventurous, conservative, and unwilling to embrace change. Antonyms for this phrase could include "innovative," "progressive," "forward-thinking," "bold," "adventurous," or "daring." Someone who is the opposite of a "stick in the mud" is a person who is willing to take risks, try new things, and embrace opportunities. They are open to new ideas and are not afraid of making mistakes. They thrive under pressure and love to explore different paths. In short, they are the kind of people who inspire others to think outside the box and follow their dreams.