Videotape
Davey had taped two men peeing on Johnny and never did anything to stop it. This is a symbol of betrayal.
Drum
Johnny is seen relentlessly drumming at the end of the play. He bangs on the drum he said was given to him by a giant that built Stone Henge. This drum is a symbol that Johnny believes in a world that the rest of society does not operate within.
X
Johnny is branded with the letter 'X' on each of his cheeks by Troy and his two thugs. The 'X' is a symbol that regardless of what he has or hasn't done that Johnny has been branded by people as bad.
Eviction Notice
Johnny is seen burning up each eviction notice he gets. This is a symbol that he doesn't recognize this law that is telling him he has to leave his home. He lives by a different set of rules.
Trivial Pursuit
Johnny begins to rattle off the answers to each Trivial Pursuit question that is asked, sometimes before a question is asked. This is a symbol that he either has a lot of time alone which he has to fill the isolation with or that he truly does have some sort of power.