The guy who goes on Urban Dictionary, finds his favorite band, and instantly adds a definition citing something ridiculous like "the best band ever in the history of music" even though anyone with an ounce of taste in music knows that particular band sucks ass.
Teenagers are the most likely to be musically challenged, with older age groups following close by.
a person who listens to the same five songs day in and day out, for months with no variation.
You know someone is musically challenged if you hear them play the same set list of limited songs, everyday, every hour of the day, no matter what mood they are in... and yet still just mutter the words when they sing.
a person who likes music but can't play an instrument or sing
Person 1: Oh so you like music? Do you play?
Person 2: Yeah I like music but I'm musically challenged