Water jet with a kink

Solution

By rubbing it with a cloth, the plastic rod is charged negatively. Charged bodies exert a force on other charges. Due to the reason that the rod is charged negatively, it attracts positive charges and repels other negative charges.

Although the water is neutrally at first, it also consists of charges. The plastic rod attracts the positive charges whereas it repels the negative ones. Therefore the atoms of the water turn and align themselves with the plastic rod.