I find by observing cats they generally do 4 basic things.
SLEEP
EAT
PLAY
CLEAN
Today we have Patty doing a through cleaning job.
Those lose cat hairs can get caught in the throat. That's the Icky part.
After all that excursion, best to recharge the battery with well deserved catnap.
Actually there is a 5th. It's everything that comes out of their mouths and asses.
Hair balls .... enough fur to make a sweater
Puke / vomit ... usually in the worst places
Crap and Piss ..... sometimes in the little box.