What the hell can you say to that? You don't want to say MONSTER because no one will ever believe that. So you have to come up with a lie that sounds just as stupid as the truth. I would have just have been better for everyone if they guy just got eaten along with the melons. Good thing for him that the monster is a vegetarian - well vegies and truck parts.
All you really can say is that you had a wicked craving for melons and didn't know when to stop. Then get another job in another state delivering pumpkins.