One tweet by Tesla's CEO seems to be having an enormous impact on WhatsApp, with many users jumping to rival messaging app Signal. Subscribe to CNET: null CNET playlists: null Download the new CNET app: https://cnet.app.link/GWuXq8ExzG Like us on Facebook: https://www.facebook.com/cnet Follow us on Twitter: https://www.twitter.com/cnet Follow us on Instagram: http://bit.ly/2icCYYm