A wedge, a shim (any object (paper, wood, cloth) that is inserted to tighten s.t. loose).
Don’t remove this wedge from the door so that it won’t be loose.
To stick s.t. into a space, insert s.t.
Stick s.t. into your broom; it is loose.
When I have money I stick it into my folded clothes.
He is inserting things into the floor because it has many holes.