What does "ball up" mean?

Roll something into a ball, as in She loved to knit and was always balling up her yarn. [Early 1800s]

Confuse or bungle, as in Jane got all balled up at the beginning of her speech, or Henry really balled up that exam. This term may come from the fact that when a horse is driven over soft or partly thawed snow, the snow becomes packed into icy balls on its hoofs, making it stumble. Another theory is that it alludes to the vulgar term balls for testicles. [First half of 1900s]