Drepetomania

It was rare to see the girl without her skateboard with her, unless it was confiscated by a professor. She would've been late to class a lot more without it. A lot of the wizards had no clue what it was she was riding and some scoffed at the sight of it, but the brunette could care less and that's what Sirius Black found the most intriguing.

Drapetomania
An overwhelming urge to runaway
An uncontrollable or insane impulsion to wonder