You’ve Been Warned
This economics professor had very strict rules for cell phones going off during his lecture. He demonstrated this by putting his old phone that he no longer uses in a jar of pickle juice and setting it on his desk to warn the students what will happen to their devices if they ring in class.
What is strange is that professors work at universities and an economics class is usually a college course. If your phone starts ringing during a college lecture, the professor can ask you to leave. However, you are an adult just like they are and they have no right to damage your property.