The post WWII Baby Boom Generation had become teenagers in the 1960s so culture was dominated by youth. The Beatlemania coined the middle of the decade and made thousands of fans getting a mop-top. -A cut with straight bangs, collar-length in the neck and covering the ears at the side that got its name because of its resemblance to a mop.
According to the “inventor” of the bowl-shaped hair do, Jürgen Vollmer, he one day just decided not to backcomb his hair as it was usual at that time but to wear them as bangs as a personal sign of rebellion against the squares.
With their messages of love and non-violence the Beatles were symbols of the 1960s counterculture and were perceived as the embodiment of progressive ideals.
In the Soviet Union wearing a mop-top was regarded as extremely rebellious and people were stopped on the street and had their hair cut in police stations.