If you rub a comb through your hair and hold it near a thin stream of water flowing from a faucet, the stream of water will deflect toward the comb. Why?
A stream of water can become charged when another charge comes near it. The negatively charged comb attracts positive charge onto the water stream and pushed negative charge off of it. As a result, the stream acquired a positive charge and the rest of the world, a negative charge. The stream deflects toward the oppositely charged comb.