McGrath, you know cats will never do those cute clever tricks when someone else is watching - they just sit there, look blank, then up a hind leg for a close inspection of their favourite bits.

Kat, I honestly think they like the sound they're making. Mine is very methodical about it, positions himself in a convenient spot, then slowly and carefully reaches a paw to a string, deploys claws, and plucks. Aaannnd... rinse and repeat, until cat boredom ensues (approximately 32 seconds).