When someone scribbles, they make quick, messy drawings or writing.
Scribbles are usually done quickly and without much care.
Examples:
She scribbles a picture of a cat.
His notebook is full of scribbles.
I scribble my name on the paper.
The little girl scribbles all over the walls with crayons.
The artist scribbles a rough sketch before starting the painting.
He scribbles a note to remind himself to buy milk.