"Become Rusty" refers to the process of becoming outdated or losing proficiency in a skill or activity. Synonyms for "become rusty" include "deteriorate", "degenerate," "decay," "atrophy," and "waste away." Other phrases include "fall out of practice," "lose one's touch," "become obsolete," and "lose one's edge." These expressions convey a similar sense of losing proficiency or failing to keep up with modern trends. It's essential to stay relevant in a fast-paced world, so it's crucial to keep practicing what we do and learn new things to keep up with the times.