Definition of "Tapper" :

noun: a dancer who sounds out rhythms by using metal taps on the toes and heels of the shoes

noun: someone who wiretaps a telephone or telegraph wire

noun: a worker who uses a tap to cut screw threads

noun: a person who strikes a surface lightly and usually repeatedly

"Finger tappers irritated her."

noun: a tavern keeper who taps kegs or casks