Trending Man Hairstyle 2021 Boy : A photo posted by men's hair (@menshair) on feb 8, 2016 at 5:07pm pst. Well the hairstyle of most teenage boys in the 90s is back in style, so why not get ahead of the game and visit your local barber for this retro cut. Man Hairstyle 2021 Boy / Faded sides with shaved line.