A person whose behavior and thinking is fad-friendly, who does not evaluate and look for deeper meaning or give much thought to long-term consequences. Impulsively follows the crowd or other trendlings down the path of least emotional resistance.
Synonyms: sheep, lemming, robot, mindless.
Antonyms: mindful, unsheeply, unsheepable, thoughtful, analytical.
Don't be such a trendbot -- think about the issues, don't just follow friends (society, culture, advertising, false revolutions, propaganda) mindlessly.