Instructions. Poke a small hole in the bottom of each cup with the push pin. Do not make the hole too large, or the string telephone will not work properly. Thread one end of the string through the hole in the bottom of one cup.Tie that end of the string to a paper clip. This prevents the string from falling out. Repeat this process with the other end of the string and the other cup.nstructions. Poke a small hole in the bottom of each cup with the push pin. Do not make the hole too large, or the string telephone will not work properly. Thread one end of the string through the hole in the bottom of one cup.