HELP I AM FREAKING OUT!!!!!!?

someone ate my last cheeseburger!! I bought 7 (six to eat for lunch, 1 for afternoon tea) and i could not find the last one!? no one could have ate it as i am the only one who lives here (except for my gran but she is super fat and sits on the couch all day, never seen her leave the couch) any suggestions? Could it be a ghost?! A phantom? Or spirit? THANKS x