Telethy was an ability that a Klayman possessed. He could use it to communicate with others using only the power of his thoughts.
In 'Klay World: Telethy', the Klayman demonstrated this ability when he unintentionally forced the insatiable desires for sandwiches into his friend Zack's head. When he attempted to remove this hunger, Zack's head exploded. It is unknown if exploding heads is an extension of Telethy, or a different power entirely.