It is never safe to mess around or yell in the car or on the bus, that is called distracting the driver. Don’t distract the driver, they need to focus on driving and keeping you safe. What if the driver has to turn around to tell you to stop messing around in the back seat? Are they watching the road? What if a car stopped in front of them? You want to make the car a safe place for everyone in the car and on the road around you, so you should never distract the driver.