Just then the full moon emerges from behind a cloud and you are bathed in it's beam. Your skin starts feeling hairy and your clothes start feeling tight.
Especially your shoes.
You're getting bigger and hairier, and your shoes are getting tighter until the strain makes them rip to pieces, and you are left with huge bare feet that rapidly expand until they fill the carved prints.
As well as size 25s you find that your body is 7 feet tall and as you run your fingers over your face you discover it to be rather apelike. You stare at your feet and wriggle your toes. You're Bigfoot all right, and the zoo isn't the best place to be caught. You're sure they'll have a cage just for you...