A person who leaves breadcrumbs in the tub of butter after spreading butter on their toast with a butter knife or any other utensil.
It can also refer to a person who leaves crumbs behind after eating.
"I see the breadcrumb culprit was using the butter again!"
1. a person who leaves a trail of crumbs in a tub of butter or butter stick while spreading butter on their carbohydrate of choice (toast, waffle, bagel, etc)
2. a person who leaves crumbs behind after eating
"Oh, it looks like the breadcrumb culprit was using the butter!"