The pile of goo has no right being that fast, but it is, and you're unable to outrun it when it happily digs into your leg and shorts. You try to shake it off, but it melts into the shorts, covering your legs with slimy squelches. You tilt, barely managing to keep your balance as something pulls from your backside, twining through the air.
Your face lengthens into a short muzzle, itching like crazy until whiskers sprout. You sneeze at the feeling, nearly falling before your new tail adjusts, a strange but not unwelcome feeling. The slime spreads up further, dripping into twitching ears and fur getting even thicker for a moment longer before the changes finally finish. Now uh, how does one live life as a cat...?