I've determined what C's problem is. She's a cat.
She plays with my knitting, bats my yarn balls across the floor, and, when caught with contraband, scurries under the furniture just out of reach. She never comes when called, but jumps unexpectedly on my lap, causing me to drop whatever I'm holding. She "accidentally" knocks into things, then gives me a look that says "I dare you". She is, even at this moment, meowing for milk.
This also conveniently explains the desire for world domination.