To go bad, means to have a bad trip.

A person having this experience is in extreme discomfort, often being sure of dying within the next moments.

This phenomenon can be caused by, but is not limited to: taking too many drugs, combining drugs, depressive thoughts.

Bad trips can be prevented: never use new drugs by yourself and moderate your drinking when you smoke weed.

If you see someone who is going bad, try to comfort them by distracting them. More often than not, this occurance is harmless and merely a thought, that the person needs to let go off.

When someone goes to the gym and spends 90% of the time on their phones scrolling through social media

To go off on someone.

You are good at something but Also bad.