YoMAMA is a simple script that sends a large amount of pre-saved messages (insults) to a Whatsapp user automatically every 2 seconds (adjustable).
Copy the script in its entirity. Navigate to web.whatsapp.com and navigate to the conversation of the user you would like to spam. Depending on your browser, you may run the script in the browser's console. In Chrome do the following: View -> Developer -> Javascript coonsole -> Then paste the script and run.