Definition of string up:
(v) :
(transitive, idiomatic) To suspend by means of rope, cord or similar material.
(v) :
(transitive, idiomatic) To concatenate; to link in a line.
(v) :
(transitive, idiomatic) To kill (a person) by hanging, especially to lynch.
(v) :
(intransitive, idiomatic, obsolete) To die by hanging.