My 9 year old son, Stevie, went as a ‘cereal’ killer this year. We stabbed small cereal boxes with a knife and then put fake blood on them and waited for it to dry. We used a larger cereal box and did the same, but then left a larger fake knife sticking out of the box which he carried.
The smaller boxes, with fake plastic knives which were spray painted to look real, were affixed to his clothes using double sided tape. He wore a black hat and black clothes and we made his face appear dirty like he had been crawling on the ground or through shrubbery to get to his next ‘victim’. He walked around telling everyone to hand over their cereal.
He was a big hit! The costume was very easy to create and very economical as he and his sisters ate the cereal, so there was not wasted money there. He loved it!