beat box Meaning to create rhythmic percussive sounds with your mouth, especially when accompanying rhymes or rapping For example Last year there was a guy on American Idol who was really good at beat boxing You do the beat box stuff and Ill bust some rhymes. ━━━━━━━━━━━━━ #Slang_of_the_Day @EnglishoftheDay @QuizoftheDay 38.1K views13:59