How much trouble could i get in?

Ok so on my bus, this my best friend who sit nexts to me on the bus has been throwing like pencils and crap like that at cars. Everyone in the bank of the bus knows about it and usually watches. Well, sometimes ill laugh while standing up to watch, but usually, including today when the incident happened, i tell him not to do it. Well he throws a piece of paper out and a 6th grader tell the bus driver on him. The bus driver comes to the back of the bus and tells my friend if hes been throwin stuff out and told him that the bus behind us saw him thrown somethin out. He asked me and everybody around me ( 3 people) if we had thrown anything out. He said he was going to review the tapes from teh camera on the bus (doubt it works). Could i get in trouble? I truly have never thrown anything out and have told my friend to stop. could i get in trouble for laughing?